Device for measuring current of three-phase inverter and method thereof

Abstract

The device for measuring current of a three-phase inverter according to the embodiment of the present application includes a current detection element connected to a lower end of one of three lower switches constituting the inverter, a current measurement unit for measuring current by using the current detection element and the other two lower switches to which the current detection element is not connected, and a current correction unit for correcting second and third current values measured using the two lower switches based on a relationship between a first current value measured using the current detection element and the second and third current values.

Description

Technical Field

[0001] This invention relates to an apparatus for measuring the current of a three-phase inverter, and more particularly to an apparatus and method for measuring the current of a three-phase inverter by using a shunt resistor and a current measurement in a switch; and an overcurrent detection circuit and method for detecting and blocking overcurrent in a control unit by adding a current sensing element. Background Technology

[0002] When measuring the three-phase current of a three-phase inverter, a single current sensor is used to measure the current. The method of using a single current sensor is widely used due to various advantages, such as cost or system size.

[0003] A three-phase inverter system using this single current sensor installs a single current sensor in the DC link and measures the current from this single current sensor. In an inverter system using a single current sensor, the single current sensor is installed in the DC link, and the signal detected by the sensor is connected to an A / D converter to measure the U, V, and W phase currents. Here, in order to measure the accurate current values ​​of two different phases, the two switching states must be maintained for a predetermined time or longer. However, there are situations where it is practically impossible to maintain the predetermined time, thus creating a problem where current measurement using a single current sensor is impossible in certain regions.

[0004] Vehicles use electricity from a battery installed within the vehicle to supply necessary power to the electronic control unit (ECU) or electronic control devices inside the vehicle. The ECU can be used for the vehicle's electric power steering (EPS) actuators and controls various devices, including motors, and especially controls devices necessary for safety. For safety reasons, precise control is important, and for this, a stable power supply must be provided to the ECU.

[0005] When overcurrent occurs due to battery power or an internal ECU malfunction, the controller within the ECU may be damaged, and problems may arise in the controller, vehicle wiring, and higher-level controllers. Overcurrent can be caused by a load exceeding the controller's capacity, a fault due to a short circuit in the controller, or inrush current. In the case of a current detection circuit that measures motor current, there is a problem that the anomaly may not be detected even if overcurrent is flowing inside the controller. Summary of the Invention

[0006] Technical topics

[0007] The technical problem to be solved by the present invention is to provide an apparatus and method for measuring the current of a three-phase inverter by using a current measurement in a shunt resistor and a switch.

[0008] Another technical problem to be solved by the present invention is to provide an overcurrent detection circuit and method for detecting and blocking overcurrent in a control unit by adding a current detection element.

[0009] The problems of this invention are not limited to those described above, and other problems not mentioned will be clearly understood by those skilled in the art from the following description.

[0010] Technical issues

[0011] An apparatus for measuring the current of a three-phase inverter according to a first embodiment of the present invention includes: a current sensing element connected to the lower end of one of the three down switches constituting the inverter; a current measuring unit that measures the current using the current sensing element and two other down switches not connected to the current sensing element; and a current correction unit that corrects the second and third current values ​​based on the relationship between a first current value measured using the current sensing element and a second and third current value measured using the two down switches.

[0012] In addition, the current sensing element may include a shunt resistor.

[0013] In addition, the current measurement unit can measure the first current value by detecting the voltage drop component of the shunt resistor.

[0014] In addition, the current measurement unit can measure the second and third current values ​​by detecting the voltage drop component of each of the two lower switches.

[0015] Alternatively, the lower switch may include a FET.

[0016] In addition, the current measurement unit can measure the second or third current value by measuring the voltage drop generated by the resistance between the drain and source terminals when the switch is turned on.

[0017] In addition, the current measurement unit can measure the second and third current values ​​by using each of the two lower switches (Rdson).

[0018] In addition, the current correction unit determines whether the peak value of the second current value or the third current value is the same as that of the first current value, and when the peak value of the second current value or the third current value is different from that of the first current value, the current correction unit can adjust the ratio of the second current value or the third current value whose peak value is different from that of the first current value.

[0019] In addition, the device for measuring the current of the three-phase inverter may also include a current control unit that uses the adjusted current value as the control signal for the inverter.

[0020] To solve the above technical problems, another embodiment of the present invention provides an apparatus for measuring the current of a three-phase inverter, comprising: three upper switches connected in parallel; three lower switches respectively connected to the three upper switches; a shunt resistor connected to the lower end of one of the three lower switches; a current measuring unit for measuring a first current value in the shunt resistor and a second and a third current value in the two lower switches not connected to the shunt resistor; and a current correction unit for correcting the second or third current value based on the first current value.

[0021] To solve the above technical problems, a current measurement method for a three-phase inverter according to a first embodiment of the present invention includes the following steps: measuring a first current value using a current sensing element connected to the lower end of one of the three lower switches constituting the inverter; measuring a second current value and a third current value using the other two lower switches that are not connected to the current sensing element; and correcting the second current value and the third current value based on the relationship between the first current value, the second current value, and the third current value.

[0022] In addition, the current sensing element may include a shunt resistor.

[0023] In addition, during the step of measuring the first current value, the voltage drop component of the shunt resistor can be detected to measure the first current value.

[0024] In addition, during the steps of measuring the second and third current values, the voltage drop component of each of the two lower switches can be detected to measure the second and third current values.

[0025] In addition, the steps of correcting the second current value and the third current value may include the following steps: determining whether the peak values ​​of the first current value and the second or third current value are the same; and when the first current value and the second or third current value are different from the peak value of the first current value, adjusting the proportion of the second or third current value whose peak value is different from the first current value based on the first current value.

[0026] In addition, in the steps of measuring the second and third current values, the second or third current value can be measured by measuring the voltage drop caused by the resistance between the drain and source terminals when the switch is turned on.

[0027] In addition, in the step of measuring the second and third current values, the second and third current values ​​can be measured by using each Rdson of the two down switches.

[0028] Additionally, the step of using the corrected current value as a control signal for the inverter may be included.

[0029] To address other technical problems, an overcurrent detection circuit according to a second embodiment of the present invention includes: a first current measuring unit for measuring the current of a terminal stage that combines a DC link current, a control unit current, and a motor drive current; a second current measuring unit for measuring the current of a motor drive unit; and a control unit that detects an overcurrent flowing through the control unit by using a first current measured by the first current measuring unit and a second current measured by the second current measuring unit, and blocks the overcurrent by reducing the output of the motor or reducing the output of the control unit.

[0030] In addition, when the first current is greater than the first threshold and the second current is greater than the second threshold, the motor output can be reduced by controlling the motor drive unit until the second current is less than or equal to the second threshold.

[0031] In addition, when the number of times the motor output is reduced is greater than or equal to a predetermined number, or when the second current does not become equal to or less than the second threshold within a predetermined time, the control unit can cut off the power input to the ECU.

[0032] In addition, when the first current is greater than the first threshold and the second current is less than or equal to the second threshold, the control unit can reduce the output of the control unit until the third current obtained by subtracting the second current from the first current becomes less than or equal to the third threshold.

[0033] In addition, when the number of times the output of the control unit is reduced is greater than or equal to a predetermined number, or when the third current does not become equal to or less than the third threshold within a predetermined time, the control unit can block the power input to the ECU.

[0034] Additionally, when an overcurrent is detected flowing in the control unit, the control unit can send an alarm to the higher-level controller.

[0035] Additionally, the first current measuring unit or the second current measuring unit may include a shunt resistor.

[0036] To address other technical problems, an overcurrent detection circuit according to another embodiment of the second embodiment of the present invention includes: a third current measuring unit for measuring DC link current; a fourth current measuring unit for measuring current of a motor drive unit; and a control unit that uses the fourth current measured by the third current measuring unit and the fifth current measured by the fourth current measuring unit to detect overcurrent, and blocks overcurrent by reducing the output of the motor or reducing the output of the control unit.

[0037] In addition, when the sixth current, which is the sum of the fourth and fifth currents, is greater than the fourth threshold and the fifth current is greater than the fifth threshold, the control unit can reduce the motor output by controlling the motor drive unit until the fifth current is less than the fifth threshold.

[0038] In addition, when the number of times the motor output is reduced is greater than or equal to a predetermined number, or when the fifth current does not become less than or equal to the fifth threshold within a predetermined time, the control unit can cut off the power input to the ECU.

[0039] In addition, when the sixth current, which is the sum of the fourth and fifth currents, is greater than the fourth threshold and the fifth current is less than or equal to the fifth threshold, the control unit can reduce the output of the control unit until the fourth current becomes less than or equal to the sixth threshold.

[0040] In addition, when the number of times the output of the control unit is reduced is greater than or equal to a predetermined number, or when the fourth current does not become less than or equal to the sixth threshold within a predetermined time, the control unit can block the power input to the ECU.

[0041] To address other technical problems, the overcurrent detection method according to a second embodiment of the present invention includes the following steps: measuring a first current flowing through a terminal stage that combines a DC link current, a control unit current, and a motor drive unit current; measuring a second current flowing in the motor drive unit; using the first and second currents to detect an overcurrent flowing through the control unit; and when an overcurrent is detected, reducing the motor output or reducing the control unit output to block the overcurrent.

[0042] In addition, during the overcurrent blocking step, when the first current is greater than the first threshold and the second current is greater than the second threshold, the motor output can be reduced by controlling the motor drive unit until the second current is equal to or less than the second threshold.

[0043] Additionally, when the number of times the motor output is reduced is greater than or equal to a predetermined number, or when the second current does not become less than or equal to a second threshold within a predetermined time, the step of blocking power input to the ECU may be included.

[0044] In addition, during the overcurrent blocking step, when the first current is greater than the first threshold and the second current is less than or equal to the second threshold, the output of the control unit can be reduced until the third current obtained by subtracting the second current from the first current becomes less than or equal to the third threshold.

[0045] Additionally, when the number of times the output of the control unit is reduced is greater than or equal to a predetermined number, or when the third current does not become less than or equal to a third threshold within a predetermined time, the step of blocking the power input to the ECU may be included.

[0046] Additionally, when an overcurrent is detected flowing in the control unit, the step of transmitting an alarm to the higher-level controller may be included.

[0047] To address other technical problems, an overcurrent detection method according to another embodiment of the second embodiment of the present invention includes the following steps: measuring a fourth current flowing in a DC link; measuring a fifth current flowing through a motor drive unit; detecting an overcurrent using the fourth and fifth currents; and when an overcurrent is detected, blocking the overcurrent by reducing the motor output or reducing the output of the control unit.

[0048] Furthermore, the overcurrent blocking step may include the following steps: when a sixth current, which is the sum of the fourth and fifth currents, is greater than a fourth threshold and the fifth current is less than or equal to the fifth threshold, the output of the control unit is reduced by controlling the drive unit until the fourth current becomes less than or equal to the sixth threshold; when the number of times the motor output is reduced is greater than or equal to a predetermined number or when the fifth current does not become less than or equal to the fifth threshold within a predetermined time, the power input to the ECU is blocked; when a sixth current, which is the sum of the fourth and fifth currents, is greater than a fourth threshold and the fifth current is less than or equal to the fifth threshold, the output of the control unit is reduced until the fourth current becomes less than or equal to the sixth threshold; and when the number of times the output of the control unit is reduced is greater than or equal to a predetermined number or when the fourth current does not become less than or equal to the sixth threshold within a predetermined time, the power input to the ECU is blocked.

[0049] Beneficial effects

[0050] According to an embodiment of the present invention, the effect of three shunt resistors can be achieved by using only one shunt resistor. Furthermore, it exhibits strong resistance to noise and torque ripple without additional shunt control. Moreover, compared to the method using three shunt resistors, it increases the accuracy of current sensing, reduces material costs, and simplifies circuit implementation.

[0051] According to embodiments of the present invention, overcurrent flowing in the control unit can be detected and blocked at an early stage. This prevents malfunctions in vehicle wiring and other electrical devices. Furthermore, the current flowing in the control unit can be continuously monitored, and any abnormalities can be sent to a higher-level controller.

[0052] The effects of the present invention are not limited to the examples above, and many more effects are included in this specification. Attached Figure Description

[0053] Figure 1 This is a block diagram of an apparatus for measuring the current of a three-phase inverter according to an embodiment of the first embodiment of the present invention.

[0054] Figure 2 An example of an apparatus for measuring the current of a three-phase inverter according to a first embodiment of the invention is shown on a three-phase inverter circuit.

[0055] Figure 3 A comparative example relative to the first embodiment of the present invention is shown.

[0056] Figure 4 and Figure 5 This is a diagram illustrating the current measurement process of a three-phase inverter according to an embodiment of the first embodiment of the present invention.

[0057] Figure 6 This is a block diagram of an apparatus for measuring the current of a three-phase inverter according to another embodiment of the first embodiment of the present invention.

[0058] Figure 7 This is a flowchart of a current measurement method for a three-phase inverter according to the first embodiment of the present invention.

[0059] Figures 8 to 11 This is a flowchart of a current measurement method for a three-phase inverter according to another embodiment of the first embodiment of the present invention.

[0060] Figure 12 This is a block diagram of an overcurrent detection circuit according to a second embodiment of the present invention.

[0061] Figure 13 An example of an implementation of an overcurrent detection circuit according to a second embodiment of the present invention is shown.

[0062] Figures 14 to 16 This is a diagram illustrating the operation of an overcurrent detection circuit according to a second embodiment of the present invention.

[0063] Figure 17 and Figure 18 A comparative example of an overcurrent detection circuit according to a second embodiment of the present invention is shown.

[0064] Figure 19 This is a block diagram of an overcurrent detection circuit according to another embodiment of the second embodiment of the present invention.

[0065] Figure 20 An example of an implementation of an overcurrent detection circuit according to another embodiment of the second embodiment of the present invention is shown.

[0066] Figure 21 and Figure 22 This is a diagram illustrating the operation of an overcurrent detection circuit according to another embodiment of the second embodiment of the present invention.

[0067] Figure 23This is a flowchart of an overcurrent detection method according to a second embodiment of the present invention.

[0068] Figures 24 to 28 This is a flowchart of an overcurrent detection method according to another embodiment of the second embodiment of the present invention. Detailed Implementation

[0069] In the following, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0070] However, the technical concept of the present invention is not limited to the embodiments to be described, but can be implemented in various forms, and within the scope of the technical concept of the present invention, one or more constituent elements can be selectively combined or replaced among the embodiments.

[0071] Furthermore, unless explicitly defined and described, the terms (including technical and scientific terms) used in the embodiments of the present invention may be interpreted as meanings commonly understood by those skilled in the art, and common terms (such as terms defined in dictionaries) may be interpreted taking into account the meaning in the context of the relevant art.

[0072] Furthermore, the terminology used in this specification is for describing embodiments and not for limiting the invention.

[0073] In this specification, unless explicitly stated in the phrase, the singular form may include the plural form, and when described as “at least one (or more) of A, B and C”, it may include one or more of all combinations that can be combined with A, B and C.

[0074] Furthermore, when describing components of embodiments of the present invention, terms such as first, second, A, B, (a), and (b) may be used. These terms are intended only to distinguish components from other components, and they do not limit the nature, order, or sequence of the components.

[0075] Furthermore, when a component is described as being “connected,” “coupled,” or “interconnected” to another component, the component is not only directly connected, coupled, or interconnected to the other component, but may also include cases where the other component is “connected,” “coupled,” or “interconnected” between the other components.

[0076] Additionally, when described as being formed or arranged "above" or "below" in each component, "above" or "below" means not only that the two components are in direct contact, but also that one or more other components are formed or arranged between the two components. Furthermore, when expressed as "above" or "below," it can include meanings based on a component that include not only the upward direction but also the downward direction.

[0077] Figure 1 This is a block diagram of an apparatus for measuring the current of a three-phase inverter according to an embodiment of the first embodiment of the present invention.

[0078] The apparatus for measuring the current of a three-phase inverter 100 according to the first embodiment of the present invention may further include a current control unit 150, which includes a current detection element 120, a current measurement unit 130 and a current correction unit 140.

[0079] The current sensing element 120 is connected to the lower end of one of the three lower switches constituting the inverter 110.

[0080] More specifically, in order to measure the three-phase current of the inverter, the current sensing element 120 is connected to the lower end of one of the three lower switches 112 that form the three-phase switch. Without connecting the current sensing element to all three lower switches 111, 112, and 113, the current sensing element 120 can be used to measure the current in all three phases by connecting it to the lower end of one of the three lower switches 112.

[0081] An inverter is a device that converts direct current (DC) to alternating current (AC). For example, in the case of operating a three-phase motor using DC power, it is used to convert the DC power into AC power suitable for the three-phase motor. Inverters can be used for various purposes, such as power inverters for motors, motor control inverters, and inverters for lighting.

[0082] An inverter may include: three upper switches connected in parallel to convert direct current (DC) to alternating current (AC); three lower switches connected to each of the three upper switches; and three nodes connected to each of the upper and lower switches to apply power to a load such as a motor. The upper and lower switches connected to each other form a half-bridge circuit and are complementary to each other, enabling the delivery of three-phase power to the load.

[0083] The three lower switches 111, 112, and 113 forming inverter 110 can be configured as FETs. FETs are field-effect transistors, which are three-electrode semiconductors with a source, drain, and gate. The current between the source and drain can be controlled by the electrostatic field generated by the voltage between the gate and source. By using these characteristics, the inverter can be used as a switching device. Inverter 110 can use FETs as lower switches.

[0084] In the case where inverter 110 is used to operate motors, etc., the current in each of the three phases can be measured, and the motor can be controlled based on the measured current. Measurement of the current in the three phases is important for accurate motor control. For the three-phase current measurement, the current sensing element 120 is connected in series to the lower terminal of one of the three lower switches.

[0085] The current sensing element 120 may include a shunt resistor. A shunt resistor is a resistor with a very low resistance value and is also called a current shunt. A shunt resistor is a resistor that divides current and is used to measure current. By connecting a shunt resistor in series with an element to measure current, the voltage generated by the resistor can be measured to measure the current. To measure current in this way, the shunt resistor may be connected in series with the lower terminal of one of the three lower switches of the inverter 110.

[0086] The current measurement unit 130 uses the current sensing element 120 and two other down switches 111 and 113 that are not connected to the current sensing element 120 to measure the current.

[0087] More specifically, in order to measure the three-phase current, the current measuring unit 130 measures the current in the other two lower switches 111 and 113 that are not connected to the current sensing element 120, and also measures the current in the current sensing element 120. The current measuring unit 130 measures the current flowing through the three-phase current in the lower switches 111, 112, and 113 of the inverter 110, and for accurate current measurement, measures the current from the current sensing element 120 connected to the lower end of one of the lower switches 112.

[0088] The current measuring unit 130 can measure current by detecting the voltage drop component when measuring the current from the current sensing element 120. When a shunt resistor is used as the current sensing element 120, the current measuring unit 130 can measure a first current value by detecting the voltage drop component of the shunt resistor.

[0089] Voltage drop means that the voltage decreases when it encounters a resistor, and it is measured as the voltage difference between the two terminals of a passive impedance. That is, voltage drop can be detected by measuring the voltage difference between the two terminals of the current sensing element 120 (i.e., the shunt resistor).

[0090] The current measuring unit 130 can measure the second and third current values ​​by detecting the voltage drop component of each of the two lower switches 111 and 113 that are not connected to the current sensing element 120. The second and third current values ​​can be measured by measuring the voltage drop at each of the lower switches 111 and 113 by measuring the voltage difference between the two ends of each of the lower switches 111 and 113.

[0091] When the current measuring unit 130 measures the second and third current values, when the current switch is turned on, the second or third current value can be measured by measuring the voltage drop caused by the resistance between the drain and source terminals. As previously described, in the inverter 110, an upper switch and a lower switch forming a half-bridge are paired and operate while conducting complementaryly to each other. To measure the current flowing through the lower switch, when the current switch is turned on, the current can be measured by measuring the voltage drop. The lower switch may include a FET, and when the current switch is turned on, the current can be measured by measuring the voltage drop that occurs between the drain and source terminals of the FET.

[0092] When measuring the second and third current values, the current measuring unit 130 can measure the second and third current values ​​using Rdson of each of the two lower switches. When the lower switches are composed of FETs, the power loss occurring in each lower switch can be expressed as the resistance Rds in the equivalent circuit. That is, when the switch is on, due to the resistance Rds, the voltage at the drain and source terminals is Vds = I*Rds, and a voltage Vds is applied across the switch. The resistance value at this time is called Rdson, and the current flowing through the switch can be measured by using the Vds voltage. In an ideal switch, Rdson (the resistance value between the drain and source when the switch is on) is 0 when on, but in actual switches, there are series resistive components. Therefore, the current can be measured by measuring the voltage drop caused by Rdson.

[0093] The current correction unit 140 corrects the second current value and the third current value based on the relationship between the first current value measured using the current sensing element 120, the second current value measured using the two lower switches 111 and 113, and the third current value.

[0094] More specifically, although the first current value measured by the current sensing element 120 is accurate, the second and third current values ​​measured using the two lower switches 111 and 113 may be inaccurate. Therefore, the current correction unit 140 corrects the second and third current values ​​based on the relationship between the first, second, and third current values.

[0095] As described above, the lower switches 111, 112, and 113 are constructed using FETs, and accurate current measurement can be difficult because Rdson, which can be used to measure the voltage drop component in the lower switches, varies depending on temperature or current magnitude. That is, the current measurement unit 130 determines whether the current measured in the lower switches 111 and 113 is accurate by comparing the current detected using the current sensing element 120 with the current measured in the lower switches 111 and 113 without the current sensing element 120, and when it is determined that the current is inaccurate, the corresponding current can be corrected to calculate an accurate current value.

[0096] When correcting the second and third current values ​​based on the relationship between the first, second, and third current values, the current correction unit 140 first determines whether the peak values ​​of the first and second or third current values ​​are the same. When the peak values ​​of the first and second or third current values ​​are different, the scale of the second or third current value whose peak value is different from the first current value can be adjusted based on the first current value.

[0097] When converting DC to AC in inverter 110, current flows through each of the three phases, and each current flowing through the three phases must actually have the same peak value. Using this, it can be determined whether a second or third current value is correct or requires correction. Specifically, it is determined whether the peak values ​​of the first and second or third current values ​​are the same. Peak value or peak-to-peak value can be used. When the peak value of the second or third current value equals the peak value of the first current value, it can be determined that the second or third current value is accurate. That is, it can be determined that correction of the current value is not necessary.

[0098] However, when the peak values ​​of the first and second or third current values ​​differ, the second or third current value, which differs from the first current value, is inaccurate, and correction is necessary. The second or third current value determined to be corrected can be corrected by adjusting the scale of the current values.

[0099] The current control unit 150 uses the calibrated current value as the control signal for the inverter.

[0100] More specifically, the current control unit 150 uses the three-phase current values ​​as control signals for the inverter 110. The current control unit 150 can use the current values ​​corrected in the current correction unit 140, for example, based on the current values ​​flowing in the three phases, to control the timing ratio of each switch included in the inverter 110.

[0101] Figure 2An example of an apparatus for measuring the current of a three-phase inverter according to a first embodiment of the invention is shown on a three-phase inverter circuit.

[0102] like Figure 2 As shown, an inverter 110 for converting DC to AC to supply power to a motor 160 may include three lower switches 111, 112, and 113, and may include a current sensing element 120 at the lower end of one lower switch 112. Here, the current sensing element 120 may be a shunt resistor. Each of the lower switches 111, 112, and 113 may be combined into a single terminal and connected to GND 170. To measure the current in the three phases, current is measured in the shunt resistor 120 and in the two lower switches 111 and 113 where the shunt resistor 120 is not connected. Each current is a current with phases u, v, and w that are different from each other. A current measuring unit 130 measures the first through third currents and can measure the current by detecting the voltage drop component in each element whose current is to be measured.

[0103] The current correction unit 140 determines whether the second and third currents are correct by comparing them with the first current measured by the current measurement unit 130, and can correct the second or third current if it is determined to be inaccurate. In determining whether the second and third currents are accurate, it can determine whether the peak values ​​of the second and third currents are the same as the peak value of the first current. The second or third current with a peak value different from the first current can be corrected.

[0104] Figure 3 This is a comparative example of the first embodiment of the present invention, and as follows Figure 2 As shown, shunt resistor 37 can be connected to the lower end of the terminals that combine all the lower switches 31, 33, and 35, instead of connecting the shunt resistor to the lower end of a single lower switch. In this case, when measuring the current, the current in each lower switch and the current in shunt resistor 120 must be measured, i.e., the current at all four locations. Gate driver ICs often only include three amplifier circuits, and in this case, an amplifier such as a separate OP-AMP is required, and four ADC channels may be necessary. After the current in the current correction unit 40 is corrected for the measured current, it is transmitted to the PWM control unit 50. Figure 3 In some cases, besides the regions where current can be measured using a shunt resistor, there are areas where measurement is impossible. Therefore, a separate algorithm is needed to compensate for these unmeasurable areas. Furthermore, when applying these algorithms, due to the transformations in the applied PWM method, it is impossible to create an accurate synthesized vector or increase the computation time in the processing unit due to the generation of asymmetric PWM, and problems such as increased noise and current ripple may occur. Additionally, with... Figure 2 The implementation of the first embodiment of the present invention is different. As the number of locations for measuring current increases, the necessary components increase accordingly. As a result, the necessary components will increase, thereby increasing the complexity of the current correction calculation in the current correction unit 140 and taking a lot of time, so it may be difficult to react or control quickly.

[0105] Figure 4 and Figure 5 This is a diagram illustrating the current measurement process of a three-phase inverter according to an embodiment of the first embodiment of the present invention, and as shown... Figure 4 As shown, the current of a three-phase inverter can be measured.

[0106] First, the voltage drop components of FETs 1 and FET 2, which are the lower switches without shunt resistors, and the voltage drop component of the shunt resistor are detected (410). Then, to increase the accuracy of the measured current, a process to determine the accuracy of the current is performed, and for this purpose, the current values ​​are compared when the currents of the three sensing components are switched (420). At this time, it is determined whether the peak values ​​of the current values ​​are the same (430). As a result of the comparison, if the peak values ​​of the current values ​​are the same, current control is performed using the measured current value without correction (440). However, as a result of the comparison, if the peak values ​​of the current values ​​are different, the FET sensing value is corrected based on the shunt resistor measurement value, and the ratio is adjusted (450). After correction, current control is performed using the corrected current value (440).

[0107] The correction process performed in the current correction unit 140 can be as follows: Figure 5 As shown.

[0108] Although the parasitic resistance component Rdson of the FET varies considerably depending on ambient temperature and current magnitude, the shunt resistance does not change significantly, so correction can be performed based on the current value in the shunt resistor. By comparing the current value Irshunt measured by the shunt resistor with the current value Irdson measured using Rdson over the same time period (510), the PI controller can control the error (e) between the two values ​​to 0. The error (e) of each measured current value (520) is measured, an integrator or multiplier is applied, and the ratio can be adjusted by feedback Rdson* to make the error 0, the ratio of Rdson* being adjusted based on the value obtained therefrom (530).

[0109] Because the two measured current values ​​have a 120-degree phase difference, control can be performed using peak or peak-to-peak values. Since the voltage drop component Rdson of the FET is a physical characteristic, it does not fluctuate rapidly, making it possible to adequately follow a control cycle that is slower than the current control cycle.

[0110] As described above, by using a single shunt resistor to measure the current in a three-phase inverter, the effect of three shunt resistors can be achieved with just one. Furthermore, with... Figure 3 Unlike traditional three-phase inverter current measurement, this method does not require an additional shunt vector control algorithm, thus exhibiting strong resistance to noise and torque ripple. Furthermore, compared to methods using three shunt resistors, it improves current accuracy, reduces material costs, simplifies circuit implementation, and enhances detection accuracy.

[0111] The three-phase inverter current measuring device according to the first embodiment of the present invention can be as follows: Figure 6 As shown in the diagram. Figure 6 The detailed description of the three-phase inverter current measuring device 100 corresponds to the above. Figures 1 to 5 The detailed description of the three-phase inverter current measuring device 100 is omitted here, therefore overlapping descriptions will be omitted.

[0112] like Figure 6 As shown, the three-phase inverter current measuring device 100 may include: three upper switches 611, 612, and 613 connected in parallel; three lower switches 621, 622, and 623 respectively connected to the three upper switches 611, 612, and 613; a shunt resistor 630 connected to the lower end of the lower switch 622 of the three lower switches 621, 622, and 623; a current measuring unit 640 for measuring a first current value in the shunt resistor 630, a second current value in the two lower switches 621 and 623 not connected to the shunt resistor 630, and a third current value; and a current correction unit 650 for correcting the second current value or the third current value based on the first current value.

[0113] Figure 7 This is a flowchart of a current measurement method for a three-phase inverter according to a first embodiment of the present invention; and Figures 8 to 11 This is a flowchart of a current measurement method for a three-phase inverter according to another embodiment of the first embodiment of the present invention. Figures 7 to 11 A detailed description of each step corresponds to Figures 1 to 6 A detailed description of the device used to measure the current of a three-phase inverter is provided, therefore repeated descriptions will be omitted. Figures 7 to 11 Each step can be performed by one or more processing units.

[0114] In order to measure the current of the three-phase inverter, firstly, in step S11, a first current value is measured using a current sensing element connected to the lower end of one of the three lower switches that constitute the inverter.

[0115] Here, the current sensing element may include a shunt resistor. When the shunt resistor is used as a current sensing element, as in step S21, the first current value can be measured by detecting the voltage drop component of the shunt resistor.

[0116] Together with or after step S11, in step S12, two additional down switches without connected current sensing elements are used to measure the second and third current values. These three phases can have a phase difference of 120 degrees, and steps S11 and S12 can be repeated and executed periodically.

[0117] When performing step S12, as in step S31, the second and third current values ​​can be measured by detecting the voltage drop component of each of the two lower switches. When the lower switch is a FET, the second or third current value can be measured by measuring the voltage drop caused by the resistance between the drain and source terminals when the lower switch is turned on, and the second and third current values ​​can be measured using each Rdson of the two lower switches.

[0118] In step S13, the second current value and the third current value are corrected based on the relationship between the first current value, the second current value and the third current value measured in steps S11 and S12.

[0119] Step S13 can be achieved through Figure 10 Steps S41 and S42 are executed. In step S41, it is determined whether the peak values ​​of the first current value and the second or third current value are the same. As a result of the determination, when the peak values ​​of the first current value and the second or third current value are different, in step S42, the ratio of the second or third current value whose peak value is different from the first current value can be adjusted based on the first current value.

[0120] Thus, the current value corrected in step S13 can be used as the control signal for the inverter in step S51.

[0121] As mentioned above, it has been referred to Figures 1 to 11 An apparatus and method for measuring the current of a three-phase inverter according to a first embodiment of the present invention are described. In the following text, reference will be made to... Figures 12 to 28An overcurrent detection circuit and method according to a second embodiment of the present invention are described. The detailed description of the overcurrent detection circuit and method according to the second embodiment of the present invention is based on an apparatus for measuring the current of a three-phase inverter according to a first embodiment of the present invention, and the methods, names, terms and functions for measuring the current of a three-phase inverter are based on the detailed description of each embodiment and may be the same as or different from each other.

[0122] In the following description, the configuration and method of the overcurrent detection circuit according to the second embodiment of the present invention will be described with reference to the accompanying drawings.

[0123] Figure 12 This is a block diagram of an overcurrent detection circuit according to a second embodiment of the present invention.

[0124] The overcurrent detection circuit 1000 according to the second embodiment of the present invention includes a first current measurement unit 1114, a second current measurement unit 1115 and a control unit 1112.

[0125] The first current measuring unit 1114 measures the current at the rear end of the terminal that combines the DC link current, control unit current, and motor drive unit current.

[0126] More specifically, to detect overcurrent in the control unit, the current flowing through components affected by or potentially affected by the current flowing through the control unit is measured. For this purpose, the first current measuring unit 1114 measures the current flowing through the DC link 1111, the current flowing through the control unit 1112, and the current at the rear end of the terminal where the current flowing through the motor drive unit 1113 is combined. The DC link 1111, control unit 1112, and motor drive unit 1113 include an ECU. An electronic control unit (ECU) is an electronic control device used in vehicles or similar applications to drive motors or control various devices within the vehicle. Because the ECU controls safety-related devices, precise control is crucial. When an overcurrent occurs in the ECU, precise control is difficult, and the overcurrent can cause damage to the ECU; therefore, it is necessary to monitor for overcurrent in the ECU. The current flowing through the ECU can be measured using the DC link current, control unit current, and motor drive unit current.

[0127] In order to simultaneously measure the DC link current, control unit current and motor drive unit current, the circuit is implemented by combining the connection lines from DC link 1111, control unit 1112 and motor drive unit 1113 connected to ground GND 1230 into a single terminal, and the first current measuring unit 1114 measures the current at the rear end of the terminal that combines the DC link current, control unit current and motor drive unit current.

[0128] The second current measuring unit 1115 measures the current of the motor drive unit 1113.

[0129] More specifically, the second current measuring unit 1115 is connected to the rear end of the motor drive unit 1113 to measure the current flowing through the motor drive unit 1113. The second current measuring unit 1115 measures the current flowing through the motor drive unit 1113 for current control in the motor drive unit.

[0130] The first current measuring unit 1114 or the second current measuring unit 1115 may include a shunt resistor. A shunt resistor is a resistor with a very low resistance value and is also called a shunt. A shunt resistor is a resistor that divides current and is used to measure current. By connecting a shunt resistor in series with a component to measure current, the voltage generated by the resistor can be measured to measure the current. The first current measuring unit 1114 can measure current by connecting a shunt resistor in series with the rear end of a terminal in which the DC link current, control unit current, and motor drive unit current are combined, and the second current measuring unit 1115 can measure current by connecting a shunt resistor in series with the motor drive unit.

[0131] The control unit 1112 detects overcurrent flowing in the control unit 1112 by using a first current measured by a first current measuring unit 1114 and a second current measured by a second current measuring unit 1115, and reduces the motor output or the output of the control unit to block the overcurrent.

[0132] More specifically, the control unit 1112 detects overcurrent flowing through it by using a first current measured by a first current measuring unit 1114 and a second current measured by a second current measuring unit 1115. When an overcurrent is detected flowing through the control unit 1112, the control unit 1112 reduces the motor output or reduces the output of the control unit, thereby blocking the overcurrent.

[0133] A preset threshold can be used to determine whether a measured or calculated current corresponds to an overcurrent. This threshold can be set differently depending on the importance or sensitivity of the device through which the overcurrent flows. Alternatively, the threshold can be set by the user. The thresholds described below can be set based on the aforementioned criteria.

[0134] When the first current is greater than the first threshold and the second current is greater than the second threshold, the control unit 1112 can control the motor drive unit to reduce the motor output until the second current becomes less than or equal to the second threshold. The control unit 1112 can detect overcurrent flowing through the control unit 1112 by comparing the first current with the first threshold.

[0135] The first current is the sum of the DC link current, the control unit current, and the motor drive unit current. When the first current exceeds a first threshold, overcurrent can also flow in the control unit 1112, and the control unit 1112 can perform overcurrent blocking processing when the first current exceeds the first threshold. When the first current exceeds the first threshold, firstly, it is determined whether a second current, which is the current flowing through the motor drive unit where a large overcurrent may occur, exceeds a second threshold. When the second current exceeds the second threshold, the motor drive unit 1113 generates an overcurrent, so the control unit 1112 can reduce the motor output by controlling the motor drive unit 1113 until the second current becomes less than or equal to the second threshold.

[0136] When reducing the motor output, the control unit 1112 can send a motor output reduction command to the motor drive unit 1113 to reduce the motor output. When the motor output decreases, it can decrease at a preset rate. For example, when the current motor output is 100%, the motor output can be sequentially reduced to 95% and 90%. The rate of decrease in motor output can vary depending on the type of motor. The rate of decrease can vary depending on the magnitude of the current motor output, or it can vary depending on the number of repetitions of the motor output reduction command. For example, as the number of repetitions of the motor output reduction command increases, the reduction rate can increase or decrease.

[0137] Motor drive unit 1113 uses electricity input from a power supply to drive motor 1220. Motor drive unit 1113 may include a three-phase inverter and a bridge circuit with six switches, converting DC power into AC power to drive motor 1220. Regarding the six switches, three upper switches and three lower switches are paired to form three half-bridge circuits, and the upper and lower switches forming the half-bridge circuits conduct complementaryly to supply power to motor 1220. The switches of the three half-bridge circuits can supply three-phase AC power to motor 1220 by operating with a 120-degree phase difference from each other. The switching operation of the switches is controlled by a time ratio.

[0138] Here, the time ratio is the ratio of the time when current flows to the time when current does not flow, and in the case of a switch, it refers to the on-time, also known as the duty cycle. That is, the motor's drive speed or drive time can be controlled by controlling the rate at which the switch is turned on. In the case of operating speed, the operating speed can be controlled by changing the degree of repeated on / off cycles within a short period. When repeating the on-off cycle, the drive speed becomes slower than when continuously on.

[0139] The control unit 1112 can reduce the motor output by controlling the timing ratio of each switch of the motor drive unit 1113. In addition to the timing ratio, various methods can be used to reduce the motor output.

[0140] When the number of times the motor output is reduced is greater than or equal to a predetermined number, or when the second current does not become equal to or less than a second threshold within a predetermined time, the control unit 1112 can block the power input to the ECU. When the second current is greater than the second threshold, an overcurrent occurs on the motor drive unit 1113 side. Therefore, to block the overcurrent, the power input to the ECU can be blocked even if the motor output is reduced by controlling the motor drive unit 1113 and the second current does not drop below the second threshold. That is, the power input from the power supply 1210 to the DC link 1111, the control unit 1112, and the motor drive unit 1113 can be blocked. To block the power input to the ECU, the power input to the ECU can be blocked by connecting a switch to the front end of the control unit 1112 or a power input unit or connector that receives power from the power supply 1210, and then by turning off the switch.

[0141] When determining whether the power input to the ECU needs to be blocked, the control unit 1112 can determine when the number of times the motor output decreases is greater than or equal to a predetermined number, or when the second current exceeds a second threshold for a predetermined time or longer. The control unit 1112 can send a motor output reduction command to the motor drive unit 1113 to reduce the motor output, and when the number of times the motor output reduction command is delivered exceeds a preset number, it determines that the overcurrent is difficult to block, and can block the power input to the ECU to protect the ECU. In this case, the number of times the motor output is reduced is set by the user; this number is a standard for blocking the power input to the ECU, or it can vary according to the sensitivity of the ECU or the required safety level. For example, if the overcurrent persists even after the motor output decreases once, the power input to the ECU can be blocked immediately, and the power input to the ECU can also be blocked after the motor output has decreased 100 times.

[0142] Alternatively, even if the overcurrent generation persists for more than a preset time, and it is determined that the overcurrent is difficult to block, the power input to the ECU can be cut off to protect the ECU. The elapsed time, which serves as the standard for cutting off the power input to the ECU, is set by the user, or it can be varied according to the sensitivity of the ECU or the required level of safety. After the motor output decreases, the time required to determine whether the second current is greater than the second threshold again can be constant, and the elapsed time can be set according to the number of repetitions of the corresponding time.

[0143] When the first current is greater than a first threshold and the second current is less than or equal to a second threshold, control unit 1112 can reduce its output until a third current, obtained by subtracting the second current from the first current, becomes less than or equal to the third threshold. When the first current is greater than the first threshold and the second current is greater than the second threshold, overcurrent has occurred in motor drive unit 1113. When the first current is greater than the first threshold and the second current is less than or equal to the second threshold, motor drive unit 1113 does not have overcurrent. This means that overcurrent has occurred in DC link 1111 or control unit 1112, excluding motor drive unit 1113. The third current, which is the sum of the DC link current (excluding motor drive unit current) and control unit current, can be calculated by subtracting the second current from the first current. Control unit 1112 can reduce its output until the third current becomes less than or equal to the third threshold. It is also possible to reduce the DC link output (excluding control unit output) or simultaneously reduce both control unit output and DC link output.

[0144] Control unit 1112 outputs various control signals for controlling devices within the ECU. Control unit 1112 may include a PMIC, MCU, gate driver IC, etc. A power management integrated circuit (PMIC) is a power management IC; a microcontroller unit (MCU) is an IC that includes a microprocessor and input / output modules; and a gate driver IC is an IC that receives low-power input from the MCU and applies power to the gate, such as an IGBT or MOSFET. Control unit 1112 can reduce its output to block overcurrent by outputting various control signals as described above. The output of control unit 1112 can be reduced by decreasing the number of control signals output from control unit 1112. Alternatively, the output of control unit 1112 can be reduced by decreasing the frequency of the output control signals. Priorities can be set according to the importance of the control signals, and control signals for reducing output can be set according to these priorities.

[0145] When the number of times the output of the control unit is reduced is equal to or greater than a predetermined number, or when the third current does not become equal to or less than the third threshold within a predetermined time, the control unit 1112 can block the current input to the ECU. To prevent overcurrent, even when the output of the control unit 1112 is reduced, the power input to the ECU can be blocked if the third current does not drop below the third threshold. That is, the power input from the power supply 1210 to the DC connection 1111, the control unit 1112, and the motor drive unit 1113 can be blocked.

[0146] When determining whether to block power input to the ECU, the control unit 1112 can determine when the number of times the control unit output decreases is greater than or equal to a predetermined number, or when the third current exceeds a third threshold for a predetermined time or longer. The control unit 1112 can command the control unit output to decrease, and when the number of times the control unit output is commanded to decrease exceeds a preset number, it is determined that overcurrent is difficult to block, and power input to the ECU can be blocked to protect the ECU. In this case, the number of times the control unit output is decreased can be set by the user, or this number can vary according to the sensitivity of the ECU or the required safety level, wherein the number of times the control unit output is decreased is the standard for blocking power input to the ECU. For example, if overcurrent persists even after the control unit output decreases once, power input to the ECU can be blocked immediately, and power input to the ECU can also be blocked after the control unit output has decreased 100 times.

[0147] Alternatively, even if the overcurrent generation persists for more than a preset time, and it is determined that the overcurrent is difficult to block, the power input to the ECU can be cut off to protect the ECU. The elapsed time, which serves as the standard for cutting off the power input to the ECU, is set by the user, or it can be varied according to the sensitivity of the ECU or the required level of safety. After the motor output decreases, the time required to determine whether the third current is greater than the third threshold again can be constant, and the elapsed time can be set according to the number of repetitions of the corresponding time.

[0148] Furthermore, when an overcurrent is detected flowing in the control unit 1112, the control unit 1112 can send an alarm to the upper-level controller. When an overcurrent is detected, the control unit 1112 can send information indicating that an overcurrent has been detected to the upper-level controller. At this time, overcurrent detection information can be delivered to the upper-level controller via an alarm. In addition to detecting overcurrent, when the power input to the ECU is blocked, information about the blocked power input to the ECU can be sent to the upper-level controller via an alarm, etc.

[0149] Figure 13 An example of an implementation of an overcurrent detection circuit according to a second embodiment of the present invention is shown; and Figures 14 to 16 This is a diagram illustrating the operation of an overcurrent detection circuit according to a second embodiment of the present invention.

[0150] Figure 13This is an example of an overcurrent detection circuit implemented in an ECU that drives a motor mounted in a vehicle. The power supply 1210 may be a battery inside the vehicle, and the motor drive unit 1113 may include a B6 bridge unit. In the motor drive unit 1113, a three-phase power supply (U-phase, V-phase, and W-phase) is applied to the motor 1220 to drive the motor. The control unit 1112 includes a PMIC, an MCU, a gate driver IC, etc., and outputs control signals to control the six switches of the motor drive unit 1113. The control unit 1112 may control the switches of the motor drive unit 1113 using a pulse width modulation (PWM) method. The DC link 1111 may include an inductor and a DC link capacitor. The lines output from the DC link 1111, the control unit 1112, and the motor drive unit 1113 to ground GND 1230 are combined and formed as a single line connected to GND 1230. In the line that combines the outputs from DC link 1111, control unit 1112, and motor drive unit 1113, a current sensing element for measuring the current of the ECU, serving as a first current measuring unit 1114, is connected to measure the total current of the ECU. In the line from the output of motor drive unit 1113 to ground GND 1230, a current sensing element for measuring the motor current, serving as a second current measuring unit 1115, is connected to measure the current of motor drive unit 1113. A shunt resistor can be used as the current sensing element.

[0151] like Figure 14 As shown, when a fault 1310 occurs in control unit 1112, an abnormal current 1320, such as overcurrent, flows in control unit 1112, and the overcurrent flowing from first current measuring unit 1114 to control unit 1112 can be measured. At this time, since the current detected by first current measuring unit 1114 is the current of the entire ECU, the motor output is first reduced by controlling motor drive unit 1113, and if the overcurrent persists even after that, the overcurrent can be blocked by reducing the output of control unit.

[0152] It is possible Figure 15 The process shown is to detect and block overcurrent. Figure 15 Each symbol and Figure 16The symbols are the same. When ECU drive (1411) starts, the number of motor unit output reduction commands H and the number of control unit output reduction commands K are initialized to 0 (1412). Thereafter, the ECU current measurement value X is measured (1413). It is determined whether the measured X is greater than the ECU current limit value B (1414). If X is less than or equal to B, continuous drive is performed (1415). If X is greater than B, an alarm is issued to the upper-level controller (1416), the motor drive unit current measurement value C is measured (1417), and it is determined whether C is greater than the motor drive unit current limit value D (1418). When C is greater than D, a command is issued for the motor output according to the motor unit output reduction ratio G (1419) to change H to H+1 (1420), and it is determined whether H is greater than the number of motor unit output reduction command limit values ​​I (1421). Then, when H is less than or equal to I, steps 417 to 421 are repeated until C is equal to or less than D. If H is greater than I, the ECU power is cut off and an alarm is sent to the upper-level controller (1422). As a result of step 418, if C is less than or equal to D, X and C are measured (1423). It is determined whether the control unit current calculation value E derived from the measured values ​​X and C (E = XC) is greater than the control unit current limit value F (1424). If E is greater than F, a reduction command for the control unit output reduction ratio J is given for the control unit output (1425), K is changed to K+1 (1426), and it is determined whether K is greater than the number L of the control unit output reduction command limit value (1427). Then, when K is L or less, steps 423 to 427 are repeated until E is equal to or less than F. If K is greater than L, the ECU power is cut off and an alarm is sent to the upper-level controller (1422). As a result of step 424, if E is less than or equal to F, it is determined that the overcurrent is blocked, and H and K are initialized (1412) to perform normal operation. The task time performed from step 412 to 422 can be less than or equal to M(1428) or less.

[0153] Figure 17 and Figure 18 A comparative example of an overcurrent detection circuit according to a second embodiment of the present invention is shown, and... Figure 13 The overcurrent detection circuit is different from the power supply 2021, which inputs power from the power supply 2021; the DC link 2011, the control unit 2012 and the motor drive unit 2013 are respectively connected to GND 2023 via separate lines; the current detection element 2015 is only connected to the motor drive unit 2013 of the drive motor 2022 to measure the motor current.

[0154] Figure 19 This is a block diagram of an overcurrent detection circuit according to another embodiment of the second embodiment of the present invention.

[0155] An overcurrent detection circuit 1800 according to another embodiment of the second embodiment of the present invention includes a third current measurement unit 1810, a fourth current measurement unit 1820 and a control unit 1112.

[0156] and Figure 12 Unlike the overcurrent detection circuit 1000 of the second embodiment of the present invention, in another embodiment of the overcurrent detection circuit 1800 according to the second embodiment of the present invention, the DC link 1111, the control unit 1112, and the motor drive unit 1113 are connected separately to the connection line to GND 1230. By including a third current measuring unit 1810 for measuring the current of the DC link and a fourth current measuring unit 1820 for measuring the current of the motor drive unit 1113, the control unit 1112 can detect and block overcurrent using the third current measuring unit 1810 and the fourth current measuring unit 1820. Since the DC link current and the motor drive unit current are significantly greater than the control unit current, and since the overcurrent of the ECU can be determined solely by measuring the DC link current and the motor drive unit current, the overcurrent can be sufficiently detected and blocked by using the third current measuring unit 1810 and the fourth current measuring unit 1820. Figure 19 In the detailed description of another embodiment of the overcurrent detection circuit according to the second embodiment of the present invention, in addition to the above, Figures 12 to 18 Apart from the different parts described in the detailed description of the overcurrent detection circuit 1000 according to the second embodiment of the present invention, the corresponding parts will be omitted below.

[0157] The third current measuring unit 1810 measures the current of the DC link 1111, and the fourth current measuring unit 1820 measures the current of the motor drive unit 1113. The third current measuring unit 1810 is connected in series to the DC link, and the fourth current measuring unit 1820 is connected in series to the motor drive unit 1113 to measure the fourth and fifth currents respectively. The fourth current measuring unit 1820 may have... Figure 12 It has the same configuration as the second current measuring unit 1115.

[0158] The control unit 1112 uses a fourth current measured by a third current measuring unit 1810 and a fifth current measured by a fourth current measuring unit 1820 to detect overcurrent, and reduces the motor output or the control unit output to block the overcurrent.

[0159] Control unit 1112 determines that when the sum of the fourth and fifth currents has a sixth current greater than a fourth threshold and the fifth current is also greater than the fifth threshold, it can control the motor drive unit to reduce the motor output until the fifth current becomes less than or equal to the fifth threshold. The sixth current, obtained by adding the fourth and fifth currents, can be used to detect the current of the entire ECU. Although the ECU current should also include the current flowing through the control unit to the fourth and fifth currents, since the current flowing through the control unit is significantly less than the fourth current flowing through the DC link, the fourth and fifth currents are used to determine the overcurrent.

[0160] To determine if an overcurrent has occurred, control unit 1112 calculates a sixth current by summing the fourth and fifth currents to determine if the sixth current exceeds a fourth threshold. When the sixth current exceeds the fourth threshold, an overcurrent occurs in the ECU. To block the overcurrent, control unit 1112 first uses the fifth current to determine if an overcurrent has been generated in motor drive unit 1113. When the fifth current exceeds the fifth threshold, it is determined that an overcurrent has occurred in motor drive unit 1113, and the motor output can be reduced by controlling motor drive unit 1113.

[0161] When the motor output is reduced more than or equal to a predetermined number of times, or when the fifth current does not become less than or equal to a fifth threshold within a predetermined time, the control unit 1112 can cut off the power input to the ECU. To prevent overcurrent, even when the output of the motor drive unit 1113 decreases, the control unit 1112 can cut off the power input to the ECU if the fifth current does not drop below the fifth threshold. That is, the power input from the power supply 1210 to the DC link 1111, the control unit 1112, and the motor drive unit 1113 can be cut off.

[0162] Alternatively, even if the overcurrent generation persists for more than a preset time, it can be determined that the overcurrent is difficult to block, and the power input to the ECU can be cut off to protect the ECU. The elapsed time, which serves as the standard for blocking the power input to the ECU, can be set by the user or varied according to the sensitivity of the ECU or the required level of safety. After the motor output decreases, since the time required to re-determine whether the fifth current is greater than the fifth threshold can be constant, the aforementioned elapsed time can be set according to the number of repetitions of the corresponding time.

[0163] When the sixth current, which is the sum of the fourth and fifth currents, is greater than the fourth threshold and the fifth current is less than or equal to the fifth threshold, control unit 1112 can reduce the output of the control unit until the fourth current is equal to or less than the sixth threshold. When the sixth current is greater than the fourth threshold and the fifth current is greater than the fifth threshold, current has already occurred in motor drive unit 1113. However, when the sixth current is greater than the fourth threshold and the fifth current is less than or equal to the fifth threshold, since no current has occurred in motor drive unit 1113, this means that current has already occurred in DC link 1111 or control unit 1112 other than motor drive unit 1113. At this time, control unit 1112 can reduce the output of control unit 1112 other than control unit output or reduce DC link output until the fourth current is equal to or less than the sixth threshold. Alternatively, control unit output and DC link output can be reduced simultaneously.

[0164] When the output of the control unit is reduced more than or equal to a predetermined number of times, or when the fourth current does not become less than or equal to the sixth threshold within a predetermined time, the control unit 1112 can block the power input to the ECU. To prevent overcurrent, even when the output of the control unit 1112 is reduced, the power input to the ECU can be blocked if the fourth current does not become equal to or less than the sixth threshold. That is, the power input from the power supply 1210 to the DC link 1111, the control unit 1112, and the motor drive unit 1113 can be blocked.

[0165] When an overcurrent is detected flowing through the control unit 1112, the control unit 1112 can send an alarm to the upper-level controller. When an overcurrent is detected, the control unit 1112 can send the detected overcurrent information to the upper-level controller. At this time, overcurrent detection information can be delivered to the upper-level controller via an alarm. In addition to overcurrent detection, when the power input to the ECU is blocked, information about the blocked power input to the ECU can be sent to the upper-level controller via an alarm, etc.

[0166] Figure 20 An example of an implementation of an overcurrent detection circuit according to another embodiment of the second embodiment of the present invention is shown, and the current detection element of the third current measurement unit 1810 is connected to the back end of the DC link 1111 and... Figure 17The circuit corresponds to the overcurrent detection circuit, and the DC link current can be measured through this circuit. When an overcurrent flows inside the ECU, the overcurrent can be detected using the current measured by the third current measurement unit 1810 and the fourth current measurement unit 1820. At this time, the current detected by the fourth current measurement unit 1820 is the motor drive unit current, and firstly, the motor output is reduced by controlling the motor drive unit 1113. If the overcurrent persists even thereafter, the overcurrent can be blocked by reducing the DC link output or the control unit output.

[0167] It is possible Figure 21 The process shown involves detecting and blocking overcurrent. Although... Figure 21 The illustration shows an example of reducing motor output or DC link output, but overcurrent can be blocked by reducing control unit outputs other than DC link output. Figure 21 Each symbol and Figure 22The symbols are the same. When ECU drive (3011) starts, the number of motor unit output reduction commands H and the number of DC link (control unit) output reduction commands K are initialized to 0 (3012). Thereafter, the motor drive unit current measurement value C and the DC link current measurement value E are measured (3013). It is determined whether the ECU current measurement value X obtained from the measured C and E (X = C + E) is greater than the ECU current limit value B (3014). If X is less than or equal to B, continuous drive is executed (3015). If X is greater than B, an alarm is issued to the upper-level controller (3016), the motor drive unit current measurement value C is measured (3017), and it is determined whether C is greater than the motor drive unit current limit value D (3018). When C is greater than D, a reduction command is issued according to the motor unit output reduction ratio G of the motor output (3019), H is changed to H+1 (3020), and it is determined whether H is greater than the number of motor unit output reduction command limit values ​​I (3021). Subsequently, when H is less than or equal to I, steps 3017 to 3021 are repeated until C is equal to or less than D. If H is greater than I, the ECU power is cut off and an alarm is issued to the upper-level controller (3022). As a result of step 3018, if C is less than or equal to D, E is measured (3023). It is determined whether the measured DC link current value E is greater than the DC link current limit value F (3024). When E is greater than F, a reduction command 3025 is issued for the DC link output according to the reduction ratio J of the DC link (control unit) output, changing K to K+1 (3026), and it is determined whether the number of DC link (control unit) output reduction command limit values ​​K is greater than L (3027). Then, when K is L or less, steps 3023 to 3027 are repeated until E is equal to or less than F. If K is greater than L, the ECU power is cut off and an alarm is issued to the upper-level controller (3022). As a result of step 1024, when E is less than or equal to F, it is determined that the overcurrent is blocked, H and K are initialized (3012), and normal operation is performed. The task time performed from step 3012 to 3022 can be less than or equal to M or less (3028).

[0168] As described above, by connecting the current sensing element to a location capable of measuring overcurrent in the control unit, overcurrent can be detected and blocked earlier when it flows due to a load heavier than the control unit's capacity, thereby protecting the internal circuitry of the control unit. Furthermore, when overcurrent flows due to a fault such as a short circuit in the control unit by altering the GND path, it can be detected and blocked earlier, thus preventing the breakdown of wiring within the vehicle and other electronic devices.

[0169] Figure 23This is a flowchart of an overcurrent detection method according to a second embodiment of the present invention; Figures 24 to 28 This is a flowchart of an overcurrent sensing method according to another embodiment of the second embodiment of the present invention. Figures 23 to 28 A detailed description of each step corresponds to Figures 12 to 22 A detailed description of the overcurrent detection circuit is provided, and therefore overlapping descriptions will be omitted. Figures 23 to 28 Each step can be performed by one or more processing units.

[0170] In order to detect overcurrent, a first current flowing through the rear end of the terminal that combines the DC link current, the control unit current and the motor drive unit current is measured in step S111, and a second current flowing through the motor drive unit is measured in step S112.

[0171] In step S113, an overcurrent flowing through the control unit is detected by using the first current and the second current measured in steps S111 and S112.

[0172] When an overcurrent is detected in step S113, the overcurrent is blocked by reducing the motor output or the control unit output.

[0173] When the first current is greater than the first threshold and the second current is greater than the second threshold, the step of blocking the overcurrent by controlling the motor drive unit can reduce the motor output until the second current becomes less than or equal to the second threshold. In addition, when the first current is greater than the first threshold and the second current is less than or equal to the second threshold, the step of blocking the overcurrent can reduce the output of the control unit until the third current obtained by subtracting the second current from the first current becomes less than or equal to the third threshold.

[0174] After measuring the first current and the second current, as Figure 24 As shown, in step S121, it is determined whether the first current is greater than the first threshold. When the first current is greater than the first threshold, the second current is greater than the first threshold. In step S122, it is determined whether the second current is greater than the second threshold. When the second current is greater than the second threshold, the motor output is reduced by controlling the motor drive unit to block the overcurrent. When the second current becomes less than the second threshold by reducing the motor output, in step S124, it is determined whether the third current is greater than the third threshold by summing the first current and the second current. When the third current is greater than the third threshold, the output of the control unit can be reduced in step S125. When the third current becomes less than or equal to the third threshold by reducing the output of the control unit, normal operation is achieved.

[0175] In addition, when the number of times the motor output is reduced is greater than or equal to a predetermined number or the second current does not become less than or equal to a second threshold within a predetermined time, the power input to the ECU can be blocked; and when the number of times the output of the control unit is reduced is greater than or equal to a predetermined number or the third current does not become equal to or less than a third threshold within a predetermined time, the power input to the ECU can be blocked.

[0176] When reducing motor output or control unit output, if it is determined that overcurrent cannot be blocked, power input to the ECU, including the DC link, control unit, and motor drive unit, can be cut off. For example... Figure 25 As shown, in step S123, the motor output is reduced by controlling the motor drive unit; in step S131, it is determined whether the number of times the motor output has been reduced is greater than or equal to a predetermined number or whether a predetermined time has elapsed; when the number of times the motor output has been reduced is greater than or equal to the predetermined number or the predetermined time has not elapsed, steps S122 to S123 are repeated; and when the number of times the motor output has been reduced is greater than or equal to the predetermined number or the predetermined time has elapsed, the power input to the ECU can be cut off. The power input to the ECU can be cut off, and an alarm can be sent to the upper-level controller. At this time, the order of steps S123 and S131 can be interchanged. That is, it can be determined whether the number of times the motor output has been reduced is greater than or equal to the predetermined number or whether a predetermined time has elapsed before the motor output is reduced.

[0177] Additionally, in step S125, the output of the control unit is reduced; in step S133, it is determined whether the number of times the control unit output has been reduced is greater than or equal to a predetermined number or whether a predetermined time has elapsed. If the number of times the control unit output has been reduced is greater than or equal to the predetermined number or the predetermined time has not elapsed, steps S124 to S125 are repeated. When the number of times the control unit output has been reduced is greater than the predetermined number or the predetermined time has elapsed, the power input to the ECU can be blocked. The power input to the ECU can be blocked, and an alarm can be sent to the upper-level controller. At this time, the order of steps S125 and S133 can be interchanged. That is, it can be determined whether the number of times the control unit output has been reduced is equal to or greater than the predetermined number or whether a predetermined time has elapsed before the control unit output is reduced.

[0178] When an overcurrent is detected flowing in the control unit in step S113, an alarm can be sent to the upper-level controller in step S141.

[0179] Figure 27 This is a flowchart of another embodiment of the overcurrent sensing method according to the second embodiment of the present invention, which corresponds to Figure 19 Methods for detecting overcurrent in overcurrent detection circuits.

[0180] In step S151, a fourth current flowing in the DC link is measured; in step S152, a fifth current flowing through the motor drive unit is measured; in step S153, overcurrent is sensed using the fourth and fifth currents. When an overcurrent is detected in step S153, the overcurrent is blocked in step S154 by reducing the motor output or the control unit output. In step S154, the output of the control unit or the DC link output may be reduced.

[0181] When the sixth current, which is the sum of the fourth and fifth currents, is greater than the fourth threshold, and when the fifth current is greater than the fifth threshold, the motor output is reduced by controlling the motor drive unit until the fifth current becomes less than or equal to the fifth threshold; when the number of times the motor output is reduced is greater than a predetermined number or the fifth current does not drop below the fifth threshold within a predetermined time, the power input to the ECU can be blocked; when the sixth current, which is the sum of the fourth and fifth currents, is greater than the fourth threshold and the fifth current is less than or equal to the fifth threshold, the output of the control unit is reduced until the fourth current becomes less than or equal to the sixth threshold; and when the number of times the output of the control unit is reduced is greater than a predetermined number or the fourth current does not drop below the sixth threshold within a predetermined time, the power input to the ECU can be blocked.

[0182] like Figure 28As shown, specific processes for detecting and blocking overcurrent can be performed. After measuring the fourth and fifth currents, in step S161, it is determined whether the sixth current, obtained by adding the fourth and fifth currents, is greater than the fourth threshold. When the sixth current is less than or equal to the fourth threshold, normal operation occurs. If the sixth current is greater than the fourth threshold, it is determined in step S162 whether the fifth current is greater than the fifth threshold. When the fifth current is greater than the fifth threshold, in step S163, the motor output can be reduced by controlling the motor drive unit. In step S164, it is determined whether the number of times the motor output is reduced is greater than or equal to a predetermined number or a predetermined time has elapsed; and if the number of times the motor output is reduced is greater than the predetermined number or the predetermined time has not elapsed, steps S162 to S163 are repeated. When the number of times the motor output is reduced is greater than the predetermined number or the predetermined time has elapsed, the power input to the ECU can be blocked. The order of steps S163 and S164 can be interchanged. As a result of the determination in step S162, if the fifth current is less than or equal to the fifth threshold, it is determined in step S166 whether the fourth current is greater than the sixth threshold. When the fourth current is less than or equal to the sixth threshold, it is determined that the overcurrent is blocked, and the overcurrent blocking process terminates and normal operation is performed. When the fourth current is greater than the sixth threshold, the output of the control unit can be reduced in step S167. The output of the DC link other than the control unit can also be reduced. In step S168, it is determined whether the number of times the control unit output (or DC link output) has been reduced exceeds a predetermined number or has elapsed for a predetermined time; and when the number of times the control unit output (or DC link output) has been reduced exceeds the predetermined number or has not elapsed for a predetermined time, steps S166 to S167 are repeated. When the number of times the control unit output (or DC link output) has been reduced exceeds the predetermined number or has elapsed for a predetermined time, the power input to the ECU can be blocked.

[0183] Modified embodiments of this embodiment may include some configurations of the first embodiment and some configurations of the second embodiment. That is, a modified embodiment may include the first embodiment, but some configurations of the first embodiment may be omitted, and some configurations of the corresponding second embodiment may be included. Alternatively, a modified embodiment may include the second embodiment, but some components of the second embodiment are omitted, and some components of the corresponding first embodiment may be included.

[0184] The features, structures, effects, etc., described in the above embodiments are included in at least one embodiment, but are not necessarily limited to one embodiment. Furthermore, the features, structures, effects, etc., shown in each embodiment can be combined or modified by those skilled in the art for other embodiments. Therefore, content related to these combinations and variations should be interpreted as being included within the scope of the embodiments.

[0185] Furthermore, embodiments of the present invention can be implemented as computer-readable code on a computer-readable recording medium. A computer-readable recording medium includes all types of recording devices that store data readable by a computer system.

[0186] Examples of computer-readable recording media include ROM, RAM, CD-ROM, magnetic tape, floppy disk, and optical data storage devices. Furthermore, these computer-readable recording media can be distributed in a distributed manner on networked computer systems capable of storing and executing computer-readable code. The functional programs, code, and code segments used to implement this invention can be readily deduced by a programmer skilled in the art to which this invention pertains.

[0187] As described above, in this invention, specific materials such as characteristic components are used; and limited embodiments and drawings have been described, but these are provided only to help to understand the invention more generally, and the invention is not limited to the above embodiments, and various modifications and variations can be made by those skilled in the art based on these descriptions.

[0188] Therefore, the spirit of the present invention should not be limited to the described embodiments, and all those that have equivalent or equivalent modifications to the claims described below are considered to be within the scope of the spirit of the present invention.

Claims

1. An apparatus for measuring current of a three-phase inverter, comprising: a current detection element connected to a lower end of one of three lower switches constituting the inverter; a current measurement unit configured to measure a current using the current detection element and two other lower switches to which the current detection element is not connected; and a current correction unit configured to correct an error of a second current value and an error of a third current value based on a relationship between a first current value measured using the current detection element and the second and third current values measured using the two lower switches. 2.The apparatus for measuring current of a three-phase inverter according to claim 1, wherein the current detection element comprises a shunt resistor. 3.The apparatus for measuring current of a three-phase inverter according to claim 2, wherein the current measurement unit measures the first current value by detecting a voltage drop component of the shunt resistor. 4.The apparatus for measuring current of a three-phase inverter according to claim 1, wherein, the current measurement unit measures the second and third current values by detecting a voltage drop component of each of the two lower switches. 5.The apparatus for measuring current of a three-phase inverter according to claim 1, wherein the lower switches are constituted by FETs. 6.The apparatus for measuring current of a three-phase inverter according to claim 1, wherein the current measurement unit measures the second or third current value by measuring a voltage drop caused by a resistance value between the drain and the source when the lower switch is turned on. 7.The apparatus for measuring current of a three-phase inverter according to claim 1, wherein, the current measurement unit measures the second and third current values by using each Rdson of the two lower switches, wherein the error of the second current value and the error of the third current value are errors of each Rdson of the two lower switches. 8.The apparatus for measuring current of a three-phase inverter according to claim 1, wherein the current correction unit determines whether the second or third current value is the same as a peak value of the first current value, and when the second or third current value is not the same as the peak value of the first current value, the current correction unit adjusts a ratio of the second or third current value whose peak value is different from the first current value. 9.The apparatus for measuring current of a three-phase inverter according to claim 1, comprising: a current control unit configured to use the adjusted current value as a control signal of the inverter. 10.An apparatus for measuring current of a three-phase inverter, comprising: three upper switches connected in parallel; three lower switches connected to the three upper switches, respectively; a shunt resistor connected to a lower switch lower end of one of the three lower switches; a current measurement unit configured to measure a first current value in the shunt resistor and second and third current values in two lower switches to which the shunt resistor is not connected; and a current correction unit configured to correct an error of a second current value and an error of a third current value based on a relationship between a first current value measured using the current detection element and the second and third current values measured using the two lower switches. a current correction unit configured to correct an error of the second current value or an error of the third current value based on the first current value.

11. The apparatus for measuring currents of a three-phase inverter according to claim 10, wherein, the current measurement unit measures the first current value by detecting a voltage drop component of the shunt resistor.

12. The apparatus for measuring currents of a three-phase inverter according to claim 10, wherein, the current correction unit determines whether the second current value or the third current value is identical to a peak value of the first current value, and when the second current value or the third current value is not identical to the peak value of the first current value, the current correction unit adjusts a ratio of the second current value or the third current value whose peak value is not identical to the first current value.

13. A current measurement method of a three-phase inverter, comprising the steps of: measuring a first current value using a current detection element connected to a lower end of one of three lower switches constituting an inverter; measuring second and third current values using the other two lower switches to which the current detection element is not connected; and correcting an error of the second current value and an error of the third current value based on a relationship between the first current value, the second current value, and the third current value.

14. The current measurement method of a three-phase inverter according to claim 13, wherein the current detection element includes a shunt resistor.

15. The current measurement method of a three-phase inverter according to claim 13, wherein in the step of measuring the first current value, the first current value is measured by detecting a voltage drop component of a shunt resistor.

16. The current measurement method of a three-phase inverter according to claim 13, wherein in the step of measuring the second and third current values, the second and third current values are measured by detecting a voltage drop component of each of the two lower switches.

17. The current measurement method of a three-phase inverter according to claim 13, wherein the step of correcting the second and third current values can include the steps of: determining whether a peak value of the first current value is identical to the second current value or the third current value; and when the second current value or the third current value is not identical to the peak value of the first current value, adjusting a ratio of the second current value or the third current value whose peak value is not identical to the first current value.

18. The current measurement method of a three-phase inverter according to claim 13, wherein, in the step of measuring the second and third current values, the second or third current value is measured by measuring a voltage drop caused by a resistance value between a drain and a source when the lower switch is turned on.

19. The current measurement method of a three-phase inverter according to claim 13, wherein, in the step of measuring the second and third current values, the second or third current value is measured by using each Rdson of the two lower switches, wherein the error of the second current value and the error of the third current value are errors of each Rdson of the two lower switches.

20. The method of current measurement for a three-phase inverter as claimed in claim 13 comprising the steps of, using the adjusted current value as a control signal for the inverter.

Images