KR102399873B1 - Apparatus and method for measuring current of 3-phase pulse width modulation(PWM) inverter - Google Patents

Abstract

A method for measuring a current of a three-phase pulse width modulation inverter according to the present invention includes a first current value of a first phase including a single current sensor, and a first voltage drop amount when a first switch located in the first phase is in a conducting state and detecting a second voltage drop amount when a second switch located in a second phase that does not include a single current sensor is in a conduction state. calculating a first resistance value Rds(on) when the first switch is in a conductive state using the first current value and the first voltage drop amount; calculating a second resistance value of the second phase according to a temperature by using the first resistance value; and calculating a second current of the second phase using the second resistance value and the second voltage drop amount.
According to the present invention, it is possible to obtain all three-phase currents required for control by applying only a single current sensor without a circuit unit increasing based on the existing three-phase pulse width modulation inverter. In addition, unlike the existing single current sensor inverter system, a separate current detection algorithm is not required, and as the system is reduced, it does not cause additional noise or harmonic characteristics degradation.

Description

Current measuring device and method of 3-phase pulse width modulation inverter {Apparatus and method for measuring current of 3-phase pulse width modulation (PWM) inverter}

The present invention relates to an apparatus for measuring a current of a three-phase pulse width modulation (PWM) inverter and a method thereof, and more particularly, to an apparatus and method for measuring a current of a three-phase pulse width modulation inverter including a single current sensor it's about

In order to measure the current of the three-phase pulse width modulation inverter, a current measuring device including a separate current sensor additionally attached to the inverter may be used.

1 is a configuration diagram for explaining a system of an inverter using a conventional single current sensor. Referring to FIG. 1 , the conventional current measuring device of the inverter 10 using a single current sensor uses a single current sensor 20 for the DC link of the inverter 10 and the signal detected by the sensor is sent to the A/D converter. It can be connected to measure U, V, W phase current.

FIG. 2 is a graph showing a current measurement time point of an inverter using a single current sensor in a space vector pulse width modulation inverter (SVPWM) method. Referring to FIG. 2 , there are a maximum of two switching states in which a current can be measured through a DC-link current during a half-cycle of the PWM.

Referring to FIG. 2 , V1 ( 100 ) denotes that the upper switch of the U phase and the lower switch of the V and W phases are turned on, and the current measurable in this section is the U phase current. V2 (110) means that the upper switch of U and V phases and the lower switch of W phase are turned on, and the current that can be measured in this section is the W phase current. In addition, different currents can be measured in each switching state. When current information of two different phases can be found in two switching states, three-phase current information can be obtained from the relational expression of Iu + Iv + Iw = 0 of the Y-connected load 30 .

Here, in order to measure an accurate current value of two different phases, two switching states must be maintained for a predetermined time or longer. However, in the actual implementation of SVPWM, it is not possible to maintain a certain time.

3 is a diagram illustrating an area in which current cannot be measured by a single current sensor on a general voltage vector plane. An area indicated in gray in FIG. 3 means a non-measurable area.

In order to remove an area that cannot be measured with such a single current sensor, conventionally, a technique of changing the pulse width modulation application time to a measurable PWM by forcibly changing it is applied. However, in the case of the method of changing the pulse width modulation application time as described above, there are problems such as not being able to create a desired accurate synthesis vector or creating an asymmetric PWM within the pulse width modulation period. In addition, this problem may affect the load control output, and there is a problem in that the amount of software operation increases according to the adjustment of the pulse width modulation application time.

Lee Woo-cheol et al. "Comparison of control method of 3-phase voltage PWM converter using single current sensor". Power Electronics Society, 2001.04.

As described above, in order to suggest a method for reducing problems such as price, volume, area, and mechanical arrangement required to apply a current sensor in a system of a three-phase pulse width modulation inverter, in the present invention, a single current sensor is provided. A current detection system with high precision and reduced compared to the existing one by detecting and calculating each current of three phases in real time using the amount of voltage drop at both ends when the switch is turned on and the resistance value (Rds(on)) when the switch is turned on. An object of the present invention is to provide an apparatus for measuring a current of a three-phase pulse width modulation inverter and a method thereof.

In order to achieve the above object, in the method for measuring a current of a three-phase pulse width modulation inverter according to the present invention, the first current value of the first phase including a single current sensor, the first switch located in the first phase is in a conducting state detecting a first voltage drop amount when the first voltage drop amount and a second voltage drop amount when a second switch positioned in a second phase that does not include a single current sensor is in a conduction state; calculating a first resistance value Rds(on) when the first switch is in a conductive state using the first current value and the first voltage drop amount; calculating a second resistance value of the second phase according to a temperature by using the first resistance value; and calculating a second current of the second phase using the second resistance value and the second voltage drop amount.

In some embodiments, the method may further include calculating a current of a third phase using the first current value and the second current value.

In some embodiments, the method may further include performing current control of the three-phase pulse width modulation inverter using the first current value and the second current value.

According to an embodiment, the process of calculating the second resistance value of the second phase according to the temperature using the first resistance value calculates the second resistance value in consideration of a change due to a change in the junction temperature of the second phase. process may include.

According to an embodiment, the first voltage drop amount is calculated as a voltage drop amount across a drain and a source of the first switch, and the second voltage drop amount is a drain and a source of the second switch. (source) It can be calculated as the amount of voltage drop across both ends.

In addition, the apparatus for measuring a current of a three-phase pulse width modulation inverter according to the present invention includes: a current detection unit for calculating a first current value of a first phase including a single current sensor; Detecting a first voltage drop amount when the first switch located in the first phase is in a conducting state and a second voltage drop amount when a second switch located in a second phase that does not include a single current sensor is in a conducting state voltage drop measuring unit; A first resistance value Rds(on) when the first switch is in a conduction state using the first current value and the first voltage drop amount and the second phase according to temperature using the first resistance value a resistance calculator for calculating a second resistance value; and a current calculator configured to calculate a second current of the second phase by using the second resistance value and the second voltage drop amount.

According to an embodiment, the current calculator may calculate the current of the third phase using the first current value and the second current value.

According to an embodiment, the control unit may further include a PWM controller configured to control the current of the three-phase pulse width modulation inverter using the first current value and the second current value.

In some embodiments, the resistance compensator may calculate the second resistance value in consideration of a variation due to a change in the junction temperature of the second phase.

According to an embodiment, the first voltage drop amount is calculated as a voltage drop amount across a drain and a source of the first switch, and the second voltage drop amount is a drain and a source of the second switch. (source) It can be calculated as the amount of voltage drop across both ends.

A current measuring apparatus and method for a three-phase pulse width modulation inverter provided as an embodiment of the present invention use a single current sensor in one of three phases and use a voltage drop at both ends when the switch is turned on for three-phase pulse width modulation Since it is possible to measure the current of each of the three phases of the inverter, the number of current sensors in the existing three-phase pulse width modulation inverter can be reduced, and the current calculation with precision while efficiently reducing the system of the three-phase pulse width modulation inverter it becomes possible

1 is a configuration diagram for explaining a system of an inverter using a conventional single current sensor.
FIG. 2 is a graph showing a point in time when a current can be measured in an inverter using a single current sensor in a space vector pulse width modulation inverter (SVPWM) method.
3 is a diagram illustrating an area in which current cannot be measured by a single current sensor on a general voltage vector plane.
4 is a flowchart illustrating a method of measuring a current of a three-phase pulse width modulation inverter according to an embodiment of the present invention.
5 is an example of a characteristic curve according to the temperature of the resistance value Rds(on) present at both ends of the switch when the switch is turned on.
6 is a diagram for explaining a relationship between a three-phase pulse width modulation inverter and a current measuring device according to an embodiment of the present invention.
7 is a view for explaining an apparatus for measuring a current of a three-phase pulse width modulation inverter according to an embodiment of the present invention.
8 shows a schematic diagram of a current detection unit configured to detect a current from an output voltage signal of a current sensor.
9 is a schematic diagram illustrating a voltage drop measurement unit that detects an amount of voltage drop at both ends when a switch of a phase to which a current sensor is applied is conducted.
FIG. 10 is a diagram for explaining the meaning of Rds(on). FIG. 10 (a) shows a general switch symbol, and (b) is a diagram for explaining a symbol equivalent to the switch of (a).
11 is a view for explaining a system of a three-phase pulse width modulation inverter according to an embodiment of the present invention.
12 is a flowchart illustrating a method of measuring a current of a three-phase pulse width modulation inverter according to an embodiment of the present invention.

Hereinafter, the terms used in this specification will be briefly described, and the configuration and operation of a preferred embodiment of the present invention will be described in detail as specific content for carrying out the present invention.

The terms used in this specification have been selected as currently widely used general terms as possible while considering the functions in the present invention, but these may vary depending on the intention or precedent of a person skilled in the art, the emergence of new technology, and the like. In addition, in a specific case, there is a term arbitrarily selected by the applicant, and in this case, the meaning will be described in detail in the description of the corresponding invention. Therefore, the term used in the present invention should be defined based on the meaning of the term and the overall content of the present invention, rather than the name of a simple term.

In the entire specification, when a part "includes" a certain element, this means that other elements may be further included, rather than excluding other elements, unless otherwise stated. In addition, terms such as "...unit" and "module" described in the specification mean a unit that processes at least one function or operation, which may be implemented as hardware or software, or a combination of hardware and software. . In addition, when a certain part is said to be "connected" with another part throughout the specification, this includes not only a case in which it is "directly connected" but also a case in which it is connected "with another configuration in the middle".

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those of ordinary skill in the art can easily carry out the present invention. However, the present invention may be implemented in several different forms and is not limited to the embodiments described herein. And in order to clearly explain the present invention in the drawings, parts irrelevant to the description are omitted, and similar reference numerals are attached to similar parts throughout the specification.

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

In order to solve the problem that occurs according to the method of using the conventional three-phase pulse width modulation (hereinafter, may be referred to as “PWM”) inverter in FIGS. 1 to 3 and a single current sensor that is DC-linked, An apparatus for measuring a current of a three-phase pulse width modulation inverter and a method thereof according to an embodiment of the present invention will be described with reference to FIGS. 4 to 11 .

The current sensor included in the current measuring device of the three-phase pulse width modulation inverter according to an embodiment of the present invention includes a Hall type, a shunt type, and a current transformer according to a current detection method. C/T) type), etc. Hall type and C/T type have high precision as a non-contact type, but they have disadvantages in terms of arrangement and design of the inverter because of their relatively high price and large volume compared to the elements used in the inverter. According to an embodiment of the present invention, it may be preferable to configure the current detection unit by applying a shunt type as an alternative to overcome this disadvantage. The shunt type has advantages in terms of economy because of its small volume and low price. However, when composing the circuit of the current measuring device, it is difficult to separate the power source, so the shunt type can be mainly applied to a low voltage system rather than a high voltage system.

For low-voltage systems that mainly use shunt type, three-phase pulse width modulation inverter Three Shunt, which applies a shunt-type current sensor to both ends of the three-phase lower switch according to the system requirements, and only two out of three phases. It can be divided into a two-shunt system that applies a shunt-type current sensor, and a one-shunt system that applies a shunt-type current sensor only to the DC DC link. As the number of shunt-type current sensors used in the 3-phase pulse width modulation inverter decreases, the price and size of the current measuring device are reduced. The one-shunt system has a disadvantage in that a separate current detection algorithm is required for current detection. In addition, even if a separate current detection algorithm is applied, there are limitations in that the software is complicated, noise is generated, and there are many harmonics in the current.

The current measuring device of a three-phase pulse width modulation inverter according to an embodiment of the present invention applies a single current sensor, but does not apply a complex separate current detection algorithm, and voltage on one of the two phases to which the current sensor is not applied. By using the configuration for measuring the amount of drop, it is possible to measure even two-phase current to which a current sensor is not applied.

On the other hand, in the three-phase pulse width modulation inverter according to an embodiment of the present invention, the conductor or each phase of the input side of the inverter may be referred to as R, S, T, and the output side of the inverter may be referred to as U, V, W. However, the present invention is not limited thereto.

In addition, the three-phase applied in the three-phase pulse width modulation inverter according to an embodiment of the present invention is configured in a Y connection (star connection) method or a delta connection method, but is not limited to the wiring method.

In addition, the switch included in the three-phase pulse width modulation inverter according to the embodiment of the present invention is a power semiconductor, a diode, a thyristor, a transistor, an insulated gate bipolar transistor (Insulated Gate Bipolar Transistor) , IGBT), gate turn-off thyristor (GTO), and metal oxide semiconductor field-effect transistor (MOSFET) It is sufficient for the configuration to perform.

4 is a flowchart for explaining a method for measuring a current of a three-phase pulse width modulation inverter according to an embodiment of the present invention, and FIG. 5 is a temperature-dependent resistance value (Rds(on)) present at both ends of the switch when the switch is turned on. It is an example of a characteristic curve, and FIG. 6 is a diagram for explaining the relationship between a three-phase pulse width modulation inverter and a current measuring device according to an embodiment of the present invention, and FIG. 7 is a three-phase pulse width modulation inverter according to an embodiment of the present invention. It is a diagram for explaining the current measuring device of the.

FIG. 5 related to the calculation of the second resistance value Rds(on) included in the flowchart of FIG. 4 will be described together with FIG. 4, and FIG. 6 and FIG. FIG. 7 will be described together with FIG. 4 .

Referring to FIG. 6 , the three-phase pulse width modulation inverter includes a single current sensor positioned in one of three phases, and any one of the voltage drop amount of the phase in which the single current sensor is positioned and the remaining two phases in which the single current sensor is not positioned. It may include a circuit for detecting the amount of voltage drop on the phase.

The current measuring device 600 according to the embodiment uses a current value detected by a single current sensor located in one of three phases and a voltage drop amount of the corresponding phase switch detected together with a resistance value (Rds) that exists when the switch is conducted (on)) can be calculated, and the change (or compensation) of the resistance value (Rds(on)) according to temperature is corrected using the real-time detected resistance value (Rds(on)) and the amount of voltage drop of another phase. In this way, the current of the inverter can be measured.

Referring to FIG. 4 , a current measuring device 600 for performing a current measuring method of a three-phase pulse width modulation inverter includes a current detecting unit 610 including a single current sensor and a voltage of a switch in a conduction state of a switch included in the inverter. The current of the three-phase pulse width modulation inverter may be measured using the voltage drop measuring unit 620 that detects the drop amount.

The conduction state according to an embodiment may refer to a state in which a semiconductor switching element such as a diode, a transistor, or a thyristor is turned on and a current flows, and may refer to a state in which all components of an electric circuit continuously maintain good contact. .

The current detection unit 610 included in the current measuring device 600 according to an embodiment is a signal detected and generated from a single current sensor (one of 511 or 512 ) located in the first phase among three phases of the inverter 500 . may be detected to calculate the first current value of the first phase (S410).

According to an embodiment, the current measuring device 600 may detect a current by applying a current sensor to only one of three phases of the inverter.

Depending on the embodiment, the single current sensor (one of 511 or 512) is one of the current sensor 512 connected in series to the upper output terminal (upper switch) or the current sensor 511 connected in series to the lower output terminal (lower switch). Either one may be used, and the current measuring device 600 may detect a current using a signal generated from a single current sensor 511 or 512 .

According to an embodiment, the current sensor may be divided into a Hall type, a shunt type, a Current Transformer (C/T) type, etc. according to a current detection method, but in this embodiment is not limited thereto.

Also, the method in which the current detector 610 according to the present embodiment detects a current using a current sensor is a general method of detecting a current of an inverter and is not limited to other current detection methods.

According to an embodiment, the current sensor may be located after the source terminal of the lower switch, and in this case, the current sensor may be a shunt type.

The voltage drop measurement unit 620 included in the current measuring device 600 according to an embodiment may include a first voltage drop amount of the first phase in which a single current sensor (one of 511 or 512) among three phases of the inverter 500 is located. can be calculated (S410).

In the current measuring device 600 according to an embodiment, the switch is in a conduction state in two of the three phases including one of the first phase in which the single current sensor is located and one of the three phases in which the single current sensor is not located. When there is, it may include a voltage drop calculation unit 620 for detecting the amount of voltage drop occurring at both ends of the switch, and using the voltage drop calculation unit 620 for each switching cycle of two of the three phases, the The amount of voltage drop that occurs during conduction can be detected.

A method of calculating the voltage drop amount of the switch in the conduction state by the voltage drop amount measuring unit 620 according to an exemplary embodiment will be described in detail with reference to FIG. 9 .

The resistance calculator 630 included in the current measuring device 600 according to an embodiment uses a first current value and a first voltage drop amount to obtain a first resistance value Rds ( on)) can be calculated (S420).

A method of calculating the first resistance value when the resistance calculator 630 according to an exemplary embodiment is in a conduction state will be described in detail with reference to FIG. 10 .

The resistance calculator 630 included in the current measuring device 600 according to an embodiment is a second phase or a second phase in which a single current sensor is not located in consideration of a compensation value in consideration of a first resistance value and a variation according to a temperature change. A second resistance value of one of the three phases may be calculated ( S430 ).

Referring to FIG. 5 , since the resistance value Rds(on) when the switch is turned on has a characteristic that varies according to the temperature, the current measuring device 600 is based on the current value previously calculated through the resistance calculator 630 . In order to solve the error, it is possible to compensate for variations in resistance (Rds(on)) depending on temperature, and by applying the relation between the current detected by a single current sensor and the amount of voltage drop across the switch, based on the phase to which the current sensor is applied. The resistance value Rds(on) under the current temperature condition may be calculated.

The resistance calculator 630 according to an exemplary embodiment may calculate the second resistance value by using a temperature-dependent characteristic curve of the resistance value Rds(on) present at both ends of the switch when the switch of FIG. 5 is turned on.

Referring to FIG. 5 , when the gate threshold voltage (V _GS ) and the drain current (I _D ) are fixed variables, when the junction temperature increases, the resistance value of the conduction state of the lower switch (Rds(on)) ) can be interpreted as increasing.

In some embodiments, the resistance calculator 630 may calculate the second resistance value using the junction temperature of a switch including a semiconductor.

The voltage drop measuring unit 620 included in the current measuring device 600 according to an embodiment is a second phase or a third in which a single current sensor (one of 511 or 512) among three phases of the inverter 500 is not located. A second voltage drop amount of any one of the phases may be calculated ( S440 ).

In the current measuring device 600 according to an embodiment, the switch is in a conduction state in two of the three phases including one of the first phase in which the single current sensor is located and one of the three phases in which the single current sensor is not located. When there is, it may include a voltage drop calculation unit 620 for detecting the amount of voltage drop occurring at both ends of the switch, and using the voltage drop calculation unit 620 for each switching cycle of two of the three phases, the The amount of voltage drop that occurs during conduction can be detected.

A method of calculating the voltage drop amount of the switch in the conduction state by the voltage drop amount measuring unit 620 according to an exemplary embodiment will be described with reference to FIG. 9 .

The current calculator 640 included in the current measuring apparatus 600 according to an embodiment may calculate a second current value by using the second resistance value and the second amount of charge ( S450 ). According to an embodiment, the current calculator 640 may calculate the second current value using Ohm's law.

The current calculator 640 included in the current measuring device 600 according to an embodiment may include a first current value of a first phase in which a single current sensor is positioned and a second or third phase in which the single current sensor is not positioned. A third current value of the remaining phase may be calculated using any one of the second current values (S460).

The current calculator 640 included in the current measuring device 600 according to an embodiment is a resistance value (Rds) corrected for the voltage drop amount and temperature change of the switch detected in one of the two phases in which a single current sensor is not located. (on)), the current can be calculated.

The resistance value Rds(on) calculated from the resistance calculation unit 630 is input to the current calculation unit 640 for measuring the current of the phase without a single current sensor, and the resistance value Rds(on) of the current calculation formula is calculated By correcting it, an accurate current can be calculated in response to the temperature fluctuation of the switch.

The current calculator 640 included in the current measuring device 600 according to an embodiment may calculate the current by using the relational expression between the voltage drop amount and the resistance value Rds(on) that exists when the switch is turned on. According to an embodiment, the current calculator 640 uses a DC-link current value, a first current value, and a second current value according to Kirchhoff's Current Law (KCL). A third current value may be calculated.

The current measuring apparatus 600 according to an exemplary embodiment may measure a current value of each of the first to third phases, and may transmit the measured current value to the PWM control apparatus 700 .

According to an embodiment, the PWM control device 700 may generate a feedback signal for controlling the three-phase pulse width modulation inverter, and may control the inverter using the feedback signal. According to an embodiment, the PWM control device 700 may control a switching speed of a switch, etc. to convert an arbitrary frequency and voltage into alternating current. According to an embodiment, the PWM control device 700 may control the current of the inverter.

S410 and S440 of FIG. 4 do not have a precedence relationship according to a time sequence, and may be performed simultaneously.

8 shows a schematic diagram of a current detection unit configured to detect a current from an output voltage signal of a current sensor.

Referring to FIG. 8 , the current detector that receives the output signal from a single current sensor located in the inverter passes a lowpass filter 611 for reducing the detection noise of the output signal, and the analog of the MCU (Micro Controller Unit) After being input to the pin and converted into a digital signal through the A/D converter 613 , the output signal may be output as a current value through the conversion unit 615 that inversely calculates and converts the signal.

9 is a schematic diagram illustrating a voltage drop measurement unit that detects an amount of voltage drop at both ends when a switch of a phase to which a current sensor is applied is conducted.

Referring to FIG. 9 , the voltage drop measuring unit 620 may be applied to both the upper switch and the lower switch.

According to an embodiment, the voltage drop measuring unit 620 includes an Op-Amp 621 for amplifying a voltage signal, an ADC 623 for performing A/D conversion, and a conversion unit 625 for converting the voltage signal. A process of converting the output voltage signal into a digital signal through A/D conversion may be performed.

The process of measuring the voltage at both ends uses the both ends of the switch as the input end of the amplifier 621 and outputs the voltage drop generated during conduction as the potential difference value of the ground reference used in the amplifier, which is an analog signal of the analog pin of the MCU. is input to a digital signal through the A/D converter 623 , and then outputs the voltage drop amount to the resistance calculator 50 through the conversion unit 625 for inverse calculation and conversion.

According to an embodiment, when the shunt-type current sensor is located under the lower switch, the current detection time can be taken only to the turn-on time of the lower switch, so the voltage drop measuring unit 620 is applied to the lower switch to detect the current. It may be easy in system design to match the timing and the timing of measuring the voltage drop.

FIG. 10 is a diagram for explaining the meaning of Rds(on). FIG. 10 (a) shows a general switch symbol, and (b) is a diagram for explaining a symbol equivalent to the switch of (a).

Referring to FIG. 10 , in an actual switch, Rds, which is a series resistance, exists. In (b), if the switch is turned on and current flows, the voltage of Vds across the switch as shown in the formula of Vds = I * Rds at the drain (D) and source (S) terminals of the switch according to the Rds resistance value. this will take The resistance value at this time is called Rds(on), and the current flowing through the switch can be measured by using the Vds voltage.

In an ideal switch, Rds(on) (resistance value between both ends of Drain and Source when the switch is turned on) is 0 when turned on, but a series resistance component exists in an actual switch. As described above, in the present invention, the current flowing when each switch is turned on by using Rds(on) can be measured by measuring the voltage generated by Rds(on). In addition, even in a non-measurable area of the conventional single current sensor (see FIG. 3 ), current measurement can be continuously performed without a separate PWM change.

11 is a diagram for explaining a system of a three-phase pulse width modulation inverter according to an embodiment of the present invention, and FIG. 12 is a flowchart for explaining a current measuring method of a three-phase pulse width modulation inverter according to an embodiment of the present invention am.

Since the current measuring method of FIG. 12 is performed by the current measuring device of FIG. 11 , FIGS. 11 and 12 will be described together.

11 and 12 , a system of a three-phase pulse width modulation inverter according to an embodiment of the present invention may include an inverter 1110 , a current measuring device 1120 , and a PWM control device 1130 .

A current measuring device 1120 according to an embodiment includes a current detecting unit 1121 that detects a first current using a current sensor 1111 or 1112 , and a first phase interlocking with the current detecting unit 1121 . When the first switch (one of the upper switch or the lower switch) conducts, the drain (Drain) and the source (Source) at both ends of the first voltage and current detection unit 1121 and the second phase of the second switch that has no interlocking relationship when conduction (Drain) ) and a first resistor present at both ends of the first switch by receiving an output value from the voltage drop measuring unit 1122 , the current detecting unit 1121 and the voltage drop measuring unit 1122 for measuring the second voltage across the first switch A resistance calculator 1123 for calculating a value, a current calculator 1125 for calculating a second current by using the first resistance value and the second voltage drop amount of the second phase that has no interlocking relationship with the current detector 1121, and The current calculator 1125 may include a resistance corrector 1124 for calculating the second resistance value of the second phase that is considered to calculate the second current.

According to an embodiment, the inverter 1110 may be a three-phase pulse width modulation inverter, and may convert the rectified voltage of the DC link terminal into AC power required by the system.

According to an embodiment, the current detection unit 1121 may be configured by selectively applying a current sensor to any one of three phases, and may detect a first current of the first phase ( S1210 ). In this case, when the current sensor 1111 or 1112 is applied to the upper output stage, all of the Hall type, C/T type, and shunt type may be applied, and when applied to the lower stage of the lower switch, only the shunt type may be applied.

According to an embodiment, the current detection unit 1121 may be configured as a simple input circuit including a passive filter (eg, an RC filter), and may have a current detection unit circuit commonly used in inverters. there is.

According to an embodiment, the first current output from the current detection unit 1121 may be fed-back to the PWM control device 1130 as a feedback signal for current control of the inverter 1110, and at the same time the resistance calculation unit ( 1123) can be entered.

The voltage drop measurement unit 1120 may measure the first voltage across the drain and source of the switch when the first switch in the first phase to which the current detection unit 1121 is applied is in a conducting state. There is (S1210).

The resistance calculator 1123 may calculate a first resistance value when the switch positioned in the first phase is turned on by using the first current and the first voltage of the first phase received from the current detector 1121 ( S1220 ). .

The resistance compensator 1124 may receive the first resistance value calculated in the previous loop, store it, and then output it to the current calculation unit 1125 in the next loop to substitute the second resistance value or calculate the second resistance value. (S1230).

The resistance compensator 1124 may replace the previous resistance value with the calculated resistance value without a separate calculation process.

The current calculation unit 1125 uses the relational expression between the first and second voltage drop amounts output from the voltage drop measurement unit 1120 and the resistance values present at both ends of the switch, the first current of the first phase and the second current of the second phase can be calculated (S1240). In this case, in order to correct the variation in the resistance value according to the temperature, the resistance correction unit 1124 may feed back the first resistance value calculated by the resistance calculation unit 1123 and continuously replace it.

The current calculator 1125 may also calculate a third current of the remaining phase among the three phases using the first current of the first phase and the second current of the second phase received from the current detector 1121 .

According to an embodiment, the current calculator 1125 may output the first to third currents to the PWM control device 1130 , and the PWM control device 1130 uses the first to third currents to generate an inverter. current control can be performed.

Meanwhile, according to an embodiment of the present invention, it is possible to provide a computer-readable recording medium in which a program for executing the above-described method in a computer is recorded. In other words, the above-described method can be written as a program that can be executed on a computer, and can be implemented in a general-purpose digital computer that operates the program using a computer-readable medium. In addition, the structure of data used in the above-described method may be recorded in a computer-readable medium through various means. A recording medium for recording an executable computer program or code for performing various methods of the present invention should not be construed as including temporary objects such as carrier waves or signals. The computer-readable medium may include a storage medium such as a magnetic storage medium (eg, a ROM, a floppy disk, a hard disk, etc.) and an optically readable medium (eg, a CD-ROM, a DVD, etc.).

Although the present invention has been described in detail through representative embodiments above, those of ordinary skill in the art to which the present invention pertains will understand that various modifications are possible within the limits without departing from the scope of the present invention with respect to the above-described embodiments. will be. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined by all changes or modifications derived from the claims and equivalent concepts as well as the claims to be described later.

Claims (10)

A method for measuring a current of a three-phase pulse width modulation inverter, the method comprising:
A first current value of a first phase including a single current sensor, a first voltage drop amount when the first switch located in the first phase is in a conducting state, and a second value in a second phase not including a single current sensor detecting a second voltage drop amount when the switch is in a conductive state at each switching period of the first switch and the second switch;
calculating a first resistance value Rds(on) when the first switch is in a conductive state using the first current value and the first voltage drop amount;
calculating a second resistance value of the second phase according to a temperature by using the first resistance value;
receiving and storing the 1-1 resistance value calculated through the first switching period;
a process of replacing the stored 1-1 resistance value with the second resistance value or newly calculating a 1-2 resistance value corrected for a change in resistance according to temperature as the second resistance value; and
and calculating a second current value of the second phase using the second resistance value and the second voltage drop amount;
The method of claim 1,
Using the first current value and the second current value, the method further comprising the step of calculating the current of the third phase, the current measuring method,
The method of claim 1,
The method further comprising the step of performing current control of the three-phase pulse width modulation inverter using the first current value and the second current value,
delete The method of claim 1,
The first voltage drop amount is calculated as a voltage drop amount across a drain and a source of the first switch,
The second voltage drop amount is calculated as a voltage drop amount across a drain and a source of the second switch.
A current measuring device for a three-phase pulse width modulation inverter, comprising:
a current detector for calculating a first current value of a first phase including a single current sensor;
A first voltage drop amount when the first switch located in the first phase is in a conductive state and a second voltage drop amount when a second switch located in a second phase that does not include a single current sensor is in a conductive state a voltage drop measuring unit detecting each switching period of the first switch and the second switch;
A first resistance value (Rds(on)) when the first switch is in a conductive state using the first current value and the first voltage drop amount, and
a resistance calculator configured to calculate a second resistance value of the second phase according to a temperature by using the first resistance value;
The first 1-1 resistance value calculated through the first switching period is received and stored, and the stored 1-1 resistance value is replaced with the second resistance value, or a change in the resistance value according to temperature is corrected. a resistance correction unit that newly calculates the -2 resistance value as the second resistance value; and
a current calculator configured to calculate a second current value of the second phase using the second resistance value and the second voltage drop amount;
7. The method of claim 6,
The current calculator,
A current measuring device for calculating a current of a third phase using the first current value and the second current value;
7. The method of claim 6,
Using the first current value and the second current value further comprising a PWM control unit for controlling the current of the three-phase pulse width modulation inverter, a current measuring device,
delete 7. The method of claim 6,
The first voltage drop amount is calculated as a voltage drop amount across a drain and a source of the first switch,
The second voltage drop amount is calculated as a voltage drop amount across a drain and a source of the second switch.

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