Apparatus and method for limiting output current using output voltage control technique

Abstract

The present disclosure provides a method for controlling an output voltage in a power supply system, including: calculating, by a virtual resistance calculator, a virtual resistance value when an output current measurement value exceeds a predetermined current limit value; calculating a signal input to the controller based on the calculated virtual resistance value; and generating, by the controller, a signal for controlling the output voltage based on the signal input to the controller.

Description

Technical Field

[0001] The present disclosure relates to a device and method for limiting output current using output voltage control technology, and more specifically, to a device and method for limiting output current using voltage control technology based on a virtual resistance element implemented as software in a power supply system such as a V2L system. Background Art

[0002] A vehicle-to-load (V2L) system is a system that uses the battery of an electric vehicle to supply power to other devices or loads. For example, the battery of an electric vehicle can be used to run home appliances or drive audio equipment during outdoor activities. In addition, the battery of an electric vehicle can be used as a temporary power source in an emergency.

[0003] However, when electronic products using commercial electricity are connected to the power supply system, they charge internal capacitors or consume higher power than the product's rated power for initial operation. From the perspective of a power supply system such as V2L, an excessive output current may occur in a short period of several seconds, damaging the power supply system. Logic to limit the output current must be implemented to prevent potential damage to the power supply system due to overcurrent.

[0004] Generally speaking, when a problem occurs in the power supply system, the corresponding output is cut off by the fail-safe logic to protect the system. However, since the main goal of the power supply system is to provide users with stable and similar power to the existing power, it may not be appropriate to cut off the output of the instantaneous overload. Therefore, logic that limits the current is required to prevent the fail-safe logic from cutting off the overcurrent.

[0005] In the related art, a method of adding a hardware driving logic circuit is used to control overcurrent in a power supply system such as a V2L system. However, there are the following problems in using hardware driving logic for overcurrent protection in a power supply system such as a V2L system.

[0006] 1. Fixed component values: In hardware-based solutions, passive components such as resistors, capacitors, or inductors are often used to set current limit values ​​and other parameters. Since these components have fixed values, it is difficult to precisely adjust or change the limits without physically replacing or modifying the components.

[0007] 2. Sensitive to component tolerances: The performance of hardware-driven logic circuits can be affected by the tolerances of the components used. Differences in component values ​​due to manufacturing tolerances can cause inconsistent system performance, making it difficult to achieve precise control and uniform operation across multiple devices.

[0008] 3. Limited adaptability: Hardware-based solutions often have limited adaptability to changes in system requirements or operating conditions. For example, modifying the current limit value requires physical changes to the circuit, which can be time-consuming and expensive.

[0009] 4. Forced cut-off of PWM output: In order to protect the power supply system from overcurrent, the PWM output is sometimes forced to be cut off, which may cause distortion of the output voltage waveform. The rapid change of the PWM signal may cause harmonic distortion and reduce the quality of the output voltage, which may affect the performance of the connected device.

[0010] 5. Increased design complexity: Integrating hardware drive logic into the power supply system may require more complex circuit design and layout as well as additional components. This may increase the overall size, weight and cost of the system while making it more difficult to achieve optimal performance.

[0011] To overcome the above problems, a new approach, such as a software-based control algorithm, is needed. Summary of the invention

[0012] In view of the foregoing, the present disclosure provides an apparatus and method for limiting the output current of a power supply system using an output voltage control technique using a virtual resistance element implemented in software.

[0013] Another object of the present disclosure is to provide an apparatus and method for converting a prior art driving logic implemented in hardware into software.

[0014] However, the technical problems to be solved by this embodiment are not limited to the above technical problems, and there may be other technical problems.

[0015] The present disclosure provides a method for limiting output current in a power supply system, comprising: when an output current measurement value exceeds a predetermined current limit value, calculating a virtual resistance value by a virtual resistance calculator; calculating a signal input to a controller based on the calculated virtual resistance value; and generating a signal for controlling an output voltage by the controller based on the signal input to the controller.

[0016] The predetermined current limit value may be a maximum current value supplied in the power supply system.

[0017] The calculation of the virtual resistance value may include: calculating a predicted load resistance value based on an output voltage measurement value and an output current measurement value; comparing the calculated predicted load resistance value with the load resistance value at maximum load; and when the load resistance value at maximum load is greater than the calculated predicted load resistance value, calculating the virtual resistance value based on the load resistance value at maximum load and the calculated predicted load resistance value, wherein when the load resistance value at maximum load is less than the calculated predicted load resistance value, the virtual resistance value may not be calculated or the virtual resistance value may be the same value as the calculated predicted load resistance value.

[0018] The calculation of the signal input to the controller may include: calculating the voltage drop of the virtual resistance based on the output current measurement value, the current limit value and the virtual resistance value; calculating the second output voltage command value based on the calculated voltage drop of the virtual resistance and the first output voltage command value; and calculating the error value based on the second output voltage command value and the output voltage measurement value, and inputting the error value to the controller.

[0019] The controller may be a proportional resonant controller defined by Equation 1 below:

[0020] Equation 1

[0021]

[0022] Where K P is the proportional gain, K i is the resonant gain, ω c is the cutoff frequency and ω c is the resonant frequency.

[0023] When generating a signal for controlling the output voltage, the signal may be generated by adjusting a pulse width modulation (PWM) duty value output from a controller.

[0024] The maximum load may be a maximum load of the maximum available power of the power supply system.

[0025] The present disclosure provides an output voltage controller, comprising: a virtual resistance calculator, configured to calculate a virtual resistance value according to an output voltage measurement value and an output current measurement value when an output current measurement value exceeds a predetermined current limit value; a signal subtractor, configured to generate a subtraction signal based on the calculated virtual resistance value and a voltage command value; and a controller, configured to generate a signal for controlling an output voltage based on the subtraction signal generated by the signal subtractor.

[0026] The predetermined current limit value may be a maximum current value supplied in the power supply system.

[0027] The virtual resistance calculator can calculate a predicted load resistance value based on an output voltage measurement value and an output current measurement value; compare the calculated predicted load resistance value with the load resistance value at maximum load; and when the load resistance value at maximum load is greater than the calculated predicted load resistance value, the virtual resistance calculator can calculate the virtual resistance value based on the load resistance value at maximum load and the predicted load resistance value, and when the load resistance value at maximum load is less than the calculated predicted load resistance value, the virtual resistance value may not be calculated or the virtual resistance value may be the same value as the calculated predicted load resistance value.

[0028] The output voltage controller can calculate the voltage drop of the virtual resistance based on the output current measurement value, the current limit value and the virtual resistance value, and the signal subtractor can include a first signal subtractor and a second signal subtractor, the first signal subtractor is configured to generate a second output voltage command value based on the calculated voltage drop of the virtual resistance and the first output voltage command value; the second signal subtractor is configured to generate an error value based on the second output voltage command value and the output voltage measurement value.

[0029] The controller may be a proportional resonant controller defined by Equation 1 below:

[0030] Equation 1

[0031]

[0032] Where K P is the proportional gain, K i is the resonant gain, ω c is the cutoff frequency and ω c is the resonant frequency.

[0033] The controller can control the output voltage by adjusting the pulse width modulation (PWM) duty cycle value.

[0034] The maximum load may be a maximum load of the maximum available power of the power supply system.

[0035] The present disclosure provides a method for limiting output current in a power supply system, comprising: calculating a virtual resistance value by a virtual resistance calculator when an output current measurement value exceeds a predetermined current limit value; calculating a signal input to a controller based on the calculated virtual resistance value; disabling a pulse width modulation (PWM) trip logic when the output current measurement value exceeds the current limit value, and enabling the PWM trip logic when the output current measurement value does not exceed the current limit value; controlling a signal output from a gate driver based on a signal generated by the controller and a signal generated by the PWM trip logic; and controlling a current transmitted to a load by controlling a switch unit based on the signal output from the gate driver.

[0036] The predetermined current limit value may be a maximum current value supplied in the power supply system.

[0037] The calculation of the virtual resistance value may include: calculating a predicted load resistance value based on an output voltage measurement value and an output current measurement value; comparing the calculated predicted load resistance value with the load resistance value at maximum load; and when the load resistance value at maximum load is greater than the calculated predicted load resistance value, calculating the virtual resistance value based on the load resistance value at maximum load and the calculated predicted load resistance value, wherein when the load resistance value at maximum load is less than the calculated predicted load resistance value, the virtual resistance value is the same value as the calculated predicted load resistance value.

[0038] The calculation of the signal input to the controller may include: calculating the voltage drop of the virtual resistance based on the output current measurement value, the current limit value and the virtual resistance value; calculating the second output voltage command value based on the calculated voltage drop of the virtual resistance and the first output voltage command value; and calculating the error value based on the second output voltage command value and the output voltage measurement value, and inputting the error value to the controller.

[0039] The maximum load may be a maximum load of the maximum available power of the power supply system.

[0040] The signal output from the gate driver may include a pulse width modulation (PWM) signal for controlling a U-phase output and a PWM signal for controlling a V-phase output.

[0041] The present disclosure provides an apparatus for limiting an output current in a power supply system, comprising: an output voltage controller, including a virtual resistance calculator, a signal subtractor, and a controller, wherein the virtual resistance calculator is configured to calculate a virtual resistance value based on an output voltage measurement value and an output current measurement value, the signal subtractor is configured to generate a subtraction signal based on the virtual resistance value and a voltage command value, and the controller is configured to generate a signal for controlling the output voltage based on the subtraction signal generated by the signal subtractor; and a pulse width modulation (PWM) trip logic, configured to control a gate driver in association with a signal from the output voltage controller, wherein the PWM trip logic is disabled when the output current measurement value exceeds a current limit value, and the PWM trip logic is enabled when the output current measurement value does not exceed the current limit value, a signal output from the gate driver is controlled based on a signal generated by the controller and a signal generated by the PWM trip logic, and a current transmitted to a load is controlled by controlling a switch unit based on the signal output from the gate driver.

[0042] The predetermined current limit value may be a maximum current value that can be supplied by the power supply system.

[0043] The virtual resistance value calculator can calculate a predicted load resistance value based on an output voltage measurement value and an output current measurement value; compare the calculated predicted load resistance value with the load resistance value at maximum load; and when the load resistance value at maximum load is greater than the calculated predicted load resistance value, calculate the virtual resistance value based on the load resistance value at maximum load and the calculated predicted load resistance value, wherein when the load resistance value at maximum load is less than the calculated predicted load resistance value, the virtual resistance value may not be calculated or the virtual resistance value may be the same value as the calculated predicted load resistance value.

[0044] The output voltage controller can calculate the voltage drop of the virtual resistance based on the output current measurement value, the current limit value and the virtual resistance value, and the signal subtractor can include a first signal subtractor and a second signal subtractor, the first signal subtractor is configured to generate a second output voltage command value based on the calculated voltage drop of the virtual resistance and the first output voltage command value; the second signal subtractor is configured to generate an error value based on the second output voltage command value and the output voltage measurement value.

[0045] The maximum load may be a maximum load of the maximum available power of the power supply system.

[0046] The signal output from the gate driver may include a pulse width modulation (PWM) signal for controlling a U-phase output and a PWM signal for controlling a V-phase output.

[0047] According to another embodiment of the present disclosure, a computer-readable storage medium stores instructions, which, when executed by a computing system including at least one processor and a memory, perform methods related to the above embodiments.

[0048] According to the present disclosure, since a complex hardware logic circuit is not required to limit the output current, the production cost can be reduced by reducing the number of devices.

[0049] Furthermore, according to the present disclosure, the voltage can be actively limited according to the magnitude of the output current.

[0050] In addition, according to the present disclosure, logic errors occurring in hardware logic can be reduced by implementing hardware gate driving logic as software.

[0051] In addition, according to the present disclosure, the current limit level can be adjusted by software without changing the device value. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 is a diagram illustrating a configuration of a power supply system including an output voltage controller according to an embodiment of the present disclosure.

[0053] Figure 2is a flowchart illustrating a method of calculating a virtual resistance component according to an embodiment of the present disclosure.

[0054] Figure 3 is a graph illustrating a simulation of output voltage control considering a virtual resistance component according to an embodiment of the present disclosure.

[0055] Figure 4 is a graph showing that an output voltage decreases as a power saw is started according to an embodiment of the present disclosure.

[0056] Figure 5 is a flow chart illustrating the operation process of the software PWM trip logic according to another embodiment of the present disclosure.

[0057] Figure 6 are graphs showing (a) AC output voltage and (b) AC output current according to an embodiment of the present disclosure.

[0058] Figure 7 is a flowchart illustrating a method of controlling an output voltage in an output voltage controller according to an embodiment of the present disclosure.

[0059] Figure 8 is a flowchart illustrating a method of limiting an output current in a power supply system according to an embodiment of the present disclosure.

[0060] Detailed description of the main components

[0061] 100: Power supply system 101: Inductor

[0062] 102: Capacitor 103: Resistor

[0063] 110: Battery 120: LLC converter

[0064] 130: switch unit 140: sensor

[0065] 150: Gate driver 160: Output voltage controller

[0066] 161: Controller 162: Virtual resistance calculator

[0067] 163: first signal subtractor 164: second signal subtractor

[0068] 165: Limiter 170: BSW

[0069] 180: PWM trip logic 190: Load DETAILED DESCRIPTION

[0070] Hereinafter, the embodiments will be described in detail with reference to the attached tables and figures so that those skilled in the art to which the present disclosure belongs can easily practice them. Since the inventive concept allows various variations and a large number of embodiments, specific embodiments will be shown in the drawings and described in detail in the written description. However, this is not intended to limit the inventive concept to a specific mode of practice, and it should be understood that all changes, equivalents and substitutions that do not depart from the scope of the inventive concept are included in the inventive concept.

[0071] In the accompanying drawings, parts not related to the description are omitted to clearly describe the present disclosure, and the same reference numerals represent the same elements throughout the specification. In the description of the accompanying drawings, elements indicated by the same name may have different reference numerals according to the accompanying drawings. The reference numerals are only for the convenience of description, and the concept, feature, function or effect of each element is not to be interpreted in a limiting manner due to its reference numeral.

[0072] When describing each accompanying drawing, the same reference numerals are used for the same elements. Terms such as first, second, etc. can be used to describe various elements, but elements are not limited by terms. These terms are only used to distinguish one constituent element from another constituent element. For example, without departing from the scope of the present disclosure, the first element can be referred to as the second element, and similarly, the second element can be referred to as the first element. The term "and / or" includes a combination of multiple associated public items or any item in multiple associated public items.

[0073] If there is no contrary definition, all terms used herein including technical or scientific terms have the same meanings as commonly understood by one of ordinary skill in the art.

[0074] Terms defined in general dictionaries should be interpreted as having meanings matching those in the context of the relevant art, and should not be interpreted as having idealized or overly formal meanings unless they are clearly defined in the application.

[0075] Throughout the specification, when a component is referred to as being "connected" to another component, it may not only be "directly connected" to the other component, but may also be "electrically connected" to the other component via an intermediate element. When a component is referred to as "comprising" a certain element, this does not exclude the existence of other elements, and other elements may be further included unless otherwise specified. It should be understood that "comprising" does not exclude the existence or addition of one or more other features, steps, numbers, operations, elements, components, and combinations thereof.

[0076] As used herein, the term "unit" or "module" includes a unit implemented by hardware or software and a unit implemented by hardware and software. One unit may be implemented using two or more hardwares, and two or more units may be implemented by one hardware.

[0077] Hereinafter, an apparatus and method for estimating an output current of a low voltage DC converter according to the present disclosure will be described in detail with reference to the accompanying drawings.

[0078] Figure 1 is a diagram illustrating a configuration of a power supply system 100 including an output voltage controller according to an embodiment of the present disclosure.

[0079] Reference Figure 1 , the power supply system 100 for controlling the output voltage may include a battery 110, an inductor-inductor-capacitor (LLC) converter 120, a switch unit 130, a sensor 140, a gate driver 150, an output voltage controller 160, a basic software (BSW) 170, a pulse width modulation (PWM) trip logic 180, a load 190, an inductor 101, a capacitor 102, a resistor 103, a controller 161, a virtual resistance calculator 162, a first signal subtractor 163, a second signal subtractor 164, and a limiter 165. In addition, the system 100 may further include Figure 1 Common components other than those shown.

[0080] The battery 110 may be, for example, a fuel cell stack, which is a group of individual fuel cells connected together. Each individual fuel cell generates a small amount of electricity, but since the individual fuel cells are combined into a stack to power an electric vehicle, sufficient electricity can be generated. Figure 1 The battery 110 may be, for example, a high voltage battery for an electric vehicle and may have the form of a fuel cell stack, but examples of the battery are not limited thereto.

[0081] The LLC converter 120 is a switch-mode power supply device that uses a resonant circuit to reduce switching losses and improve efficiency. "LLC" represents a configuration of a resonant tank circuit including two inductors L and one capacitor C. The LLC converter 120 operates by changing the frequency to control the energy transfer from input to output. At the resonant frequency of the LLC converter 120, the reactive elements (inductor and capacitor) can essentially cancel each other, so power can be transferred from the primary side to the secondary side with almost no loss. Frequency modulation combined with the zero voltage switching (ZVS) or zero current switching (ZCS) characteristics of the LLC converter 120 significantly reduces switching losses and electromagnetic interference (EMI), so it is very efficient, especially at higher power levels.

[0082] The switch unit 130 may include, for example, a full-bridge switch including four MOSFET switches. The output of the switch unit 130 is connected to the load 190, the inductor 101 is connected in series between the output of the switch unit and the load, and the capacitor 102 and the resistor 103 are connected in parallel. The output voltage V at the load 190 can be measured across the connection capacitor 102 and the resistor 103. o_sen .

[0083] The four MOSFET switches included in the switching unit 130 may be controlled by a PWM signal PWM_U_out for controlling a U-phase output and a PWM signal PWM_V_out for controlling a V-phase output, and these signals are transmitted from the gate driver 150 .

[0084] The sensor 140 can measure the input voltage V input to both ends of the switch unit 130. in_sen and the output voltage V across the load o_sen and can measure the output current i from the input to the load o_sen The output voltage V measured by the sensor 140 o_sen and the output current i o_sen It can be an input signal of the virtual resistance calculator 162 . Figure 1 The illustrated sensors show an embodiment for measuring voltage or current, and those skilled in the art may modify the number and measurement targets of the sensors as needed.

[0085] The gate driver 150 serves as an interface between the control signal and the switch unit 130 (eg, a full-bridge switch).

[0086] In the following, the following will be described in detail Figure 1 The output voltage controller 160 may include a controller 161, a virtual resistance calculator 162, a first signal subtractor 163, a second signal subtractor 164, and a limiter 165, and may further include additional elements.

[0087] Reference Figure 1 The output voltage controller 160 operates to measure the output voltage V o_sen and the output current i o_sen is input to the virtual resistance calculator 162. The virtual resistance calculator 162 calculates the virtual resistance component and outputs the virtual resistance. Figure 2 A virtual resistance calculation method of the virtual resistance calculator is described in detail.

[0088] Based on the output current i measured by the sensor 140 o_sen and the current limit value i o_limit , the voltage drop V of the virtual resistance component can be calculated by the following equation 1R Voltage drop indicates how much the output voltage needs to be regulated to keep the system operating within safe limits. Current limit refers to the maximum current that the power supply system can supply.

[0089] (Equation 1)

[0090] v R =(i o_sen -i o_limit )EstVutual_R

[0091] Among them, i o_sen is the output current value measured by the sensor, i o_limit is the current limit value, and EstVutual_R is the calculated virtual resistance value.

[0092] Considering the voltage drop of the virtual resistance component calculated by Equation 1 and the command V from the voltage controller o_Ref The voltage command V o_cmp Calculated by Equation 2 below.

[0093] (Equation 2)

[0094] V o_cmp =V o_ref -v R =V o_ref -(i o -i o_limit )EstVutual_R

[0095] The V calculated by Equation 2 o_cmp The measured value of the output voltage is used to generate an error value, and the generated error value is input to the controller 161. Thereafter, the controller 161 can control the output voltage V by controlling the PWM duty cycle value. o_sen By using this method, the output voltage can be controlled by utilizing the virtual resistance component, and finally the output current can be controlled to decrease due to the decrease of the output voltage.

[0096] Figure 1 The controller 161 included in the output voltage controller 160 shown may be a proportional resonant controller. The proportional resonant controller is a control algorithm used in a variety of applications including electric vehicles (EVs). In this specification, the proportional resonant controller defined by the following equation 3 may be used.

[0097] (Equation 3)

[0098]

[0099] Where K p is the proportional gain, K i is the resonant gain, ωc is the cutoff frequency and ω z is the resonant frequency.

[0100] The proportional resonant controller defined by Equation 3 presented as an example in this specification has excellent control performance for a specific frequency component, and exhibits characteristics suitable for voltage control of the same frequency component as that of commercial power.

[0101] The output voltage controller 160, the basic software (BSW) 170 and the PWM trip logic 180 are organically connected to operate. That is, the PWM trip logic 180 generates a trip signal when the output current measurement value i o_sen Exceeding the current limit value i o_limit The PWM trip logic is disabled when the output current measurement value does not exceed the current limit value i o_limit The current from the gate driver 150 may be controlled based on a signal generated by the output voltage controller 160 and a signal generated by the PWM trip logic 180 .

[0102] Figure 2 is a flowchart illustrating a method of calculating a virtual resistance component according to an embodiment of the present disclosure.

[0103] Reference Figure 2 , first, in operation S210, a predicted load resistance value is calculated according to an output voltage measurement value measured by a sensor and a current measurement value measured by the sensor.

[0104] Next, in operation S220, the estimated load resistance and the maximum load resistance are compared to determine whether the estimated resistance is greater than the maximum load resistance. Here, the maximum load resistance may refer to a load resistance value of the maximum power that the power supply system can supply, but may be changed to an acceptable value according to the design of those skilled in the art.

[0105] If the resistance value of the maximum load resistance is greater than the predicted load resistance value, the virtual resistance component is calculated. That is, the virtual resistance value as the virtual resistance component is calculated by obtaining the difference between the predicted load resistance value and the maximum load resistance value. If the resistance value of the maximum load resistance is not greater than the predicted load resistance value, the system operates within a stable range, so the virtual resistance component is not calculated.

[0106] Using the virtual resistance value calculated in this way, the voltage command V taking into account the virtual resistance component is obtained by the above equations 1 and 2. o_cmp. The voltage command generally refers to the guidance for the desired output voltage level in the system. In operation S230, the calculated voltage command Vo_cmp and the measured value of the output voltage are used to generate an error value as a signal input to the controller. The error value generally represents the difference between the desired output voltage and the actual output voltage. Finally, in operation S240, the generated error value is input to the controller 161 to generate a signal for controlling the output voltage, so that the controller 161 can control the output voltage. The use of virtual resistors allows for more accurate and responsive control of the output voltage, thereby improving the overall performance and reliability of the power supply system.

[0107] Figure 3 is a graph illustrating a simulation of output voltage control considering a virtual resistance component according to an embodiment of the present disclosure.

[0108] exist Figure 3 , it is shown that the AC output current exceeds the output current limit value around 0.1 seconds, which is the time point when the 10kW load is applied, and since the AC output voltage and the command are changed here, the output voltage is limited. That is, the interval A (about 0.1 seconds to 0.12 seconds) first indicated by the dotted line from 0.1 seconds is the interval in which the virtual resistance value is estimated due to the AC output current exceeding the output current limit value. In this interval, it can be seen that the output voltage is reduced due to the voltage drop caused by the virtual resistance.

[0109] The interval B (about 0.12 seconds to 0.3 seconds) indicates the interval in which the estimation of the virtual resistance component is completed. That is, since the voltage drop caused by the virtual resistance is constant, the output voltage can also be controlled to a certain level.

[0110] Interval C (after about 0.3 seconds) represents an interval where the load is removed and the output voltage is restored, and in this interval, the virtual resistance component is removed to restore the output voltage to its original state. That is, the system is stable and the AC output is restored to its original state. This means that the output voltage and current are restored to the previous levels before the 10kW load was applied.

[0111] Figure 4 is a graph showing that the output voltage decreases as the electric saw is started according to an embodiment of the present disclosure.

[0112] exist Figure 4 In the figure, the area around -1s is enlarged and shown. After the load is connected, the current exceeds the lower limit of the current limit (-53.1A) at -1.000037s, and the voltage (pink sine wave) drops.

[0113] Figure 5 is a flow chart illustrating the operation of the software PWM trip logic of the present disclosure.

[0114] Reference Figure 5 , in operation S510, it is determined whether the output current measured by the sensor is greater than the trip current level, and when it is determined that the output current is greater than the trip current level, PWM is disabled in operation S520. At this time, the PWM low output of the inverter is maintained. In addition, the switch of the inverter is maintained in the OFF state. This means that the duty cycle of the PWM signal has been reduced. Therefore, the output voltage is reduced, and therefore the current is also reduced.

[0115] Thereafter, in operation S530, when it is determined that the output current is not greater than the trip current level, the PWM trip logic is re-enabled in operation S540. At this time, the PWM of the inverter maintains normal output. That is, the duty cycle of the PWM signal is restored to a normal value. Therefore, the output voltage and current are restored to normal levels.

[0116] Figure 6 are graphs showing (a) AC output voltage and (b) AC output current according to an embodiment of the present disclosure.

[0117] Reference Figure 6 , it can be seen that the AC output voltage is output at a constant value, and then the output voltage begins to decrease from the time point when the output voltage exceeds the current limit value around 80ms. That is, when the output current is greater than the current limit value, the PWM trip logic is activated, the inverter switch is maintained in the OFF state, and the inverter PWM maintains a low output.

[0118] Specifically, when the AC output current does not exceed the output limit value, the AC voltage is output as a constant value. This generally corresponds to the required operation of the inverter, because a consistent voltage should be provided regardless of the load to which the power is supplied.

[0119] However, at about 80ms, which is the point in time when the load is connected, the current starts to exceed the predetermined limit. Here, when the current limit is exceeded, the PWM trip logic is activated to reduce the output voltage. At this time, the inverter switch is in the OFF state, and the inverter PWM maintains a low output. This means that the duty cycle of the PWM signal is reduced, so that the output voltage and current are reduced, and it is a protective measure to prevent overcurrent from being supplied to the system.

[0120] Figure 7 is a flow chart illustrating a method of controlling an output voltage by an output voltage controller according to an embodiment of the present disclosure.

[0121] First, in operation S710, when the measured value of the output current exceeds a predetermined current limit value, a virtual resistance value is calculated by a virtual resistance calculator. Here, the predetermined current limit value refers to a maximum current value that can be supplied by the power supply system.

[0122] As an example, the operation S710 of calculating the virtual resistance value may include: calculating the predicted load resistance value according to the output voltage measurement value and the output current measurement value; comparing the calculated predicted load resistance value with the load resistance value at the maximum load; and when the load resistance value at the maximum load is greater than the calculated predicted load resistance value, calculating the virtual resistance value according to the load resistance value at the maximum load and the calculated predicted load resistance value. If the load resistance value at the maximum load is less than the calculated predicted load resistance value, the virtual resistance value may not be calculated or the virtual resistance value may have the same value as the calculated predicted load resistance value.

[0123] Next, in operation S720, a signal input to a controller is calculated based on the calculated virtual resistance value.

[0124] As an example, the operation (S720) of calculating a signal input to the controller may include: calculating a voltage drop of a virtual resistor based on an output current measurement value, a current limit value, and a virtual resistance value; calculating a second output voltage command value based on the calculated voltage drop of the virtual resistor and a first output voltage command value; and calculating an error value based on the second output voltage command value and the output voltage measurement value, and inputting the error value to the controller.

[0125] Next, in operation S730, the controller generates a signal for controlling the output voltage based on the signal input to the controller. As an example, the generation of the signal for controlling the output voltage may be performed by adjusting a PWM duty value output from the controller.

[0126] On the other hand, it should be noted that it is possible to modify Figure 7 The order of operations in the embodiment of the present invention is described in detail, and technicians in this field can modify the timing sequence according to the design requirements.

[0127] Figure 8 is a flowchart illustrating a method of limiting an output current in a power supply system according to an embodiment of the present disclosure.

[0128] First, in operation S810, when the output current measurement value exceeds a predetermined current limit value, the virtual resistance calculator calculates a virtual resistance value. Here, the predetermined current limit value refers to a maximum current value that can be supplied in the power supply system.

[0129] As an example, the operation of calculating the virtual resistance value (S810) may include: calculating a predicted load resistance value based on the output voltage value and the output current measurement value; comparing the calculated predicted load resistance value with the load resistance value at the maximum load; and when the load resistance value at the maximum load (e.g., the maximum load of the maximum available power in the power supply system) is greater than the calculated predicted load resistance value, calculating the virtual resistance value based on the load resistance value at the maximum load and the calculated predicted load resistance value. If the load resistance value at the maximum load is less than the calculated predicted load resistance value, the virtual resistance calculator may not calculate the virtual resistance value or may use the same value as the calculated predicted load resistance value.

[0130] Next, in operation S820, a signal input to the controller is calculated based on the virtual resistance value.

[0131] As an example, operation S820 of calculating a signal input to a controller may include: calculating a voltage drop of a virtual resistor based on an output current measurement value, a current limit value, and a virtual resistance value; calculating an updated output voltage command value based on the calculated voltage drop of the virtual resistor and an output voltage command value, the updated output voltage command value taking into account the virtual resistance component; calculating an error value based on the updated output voltage command value and the output voltage, and inputting the calculated error value into the controller.

[0132] Next, in operation S830 , the PWM trip logic is disabled when the output current measurement value exceeds a predetermined current limit value, and the PWM trip logic is enabled when the output current measurement value does not exceed the current limit value.

[0133] Next, in operation S840, the signal output from the gate driver is controlled based on the signal generated by the controller and the signal generated by the PWM trip logic. Here, the signal output from the gate driver may include a PWM signal for controlling the U-phase output and a PWM signal for controlling the V-phase output.

[0134] Next, in operation S850, current delivered to the load is controlled by controlling the switching unit based on a signal output from the gate driver.

[0135] On the other hand, it should be noted that those skilled in the art can change the Figure 8 The timing sequence of each operation.

[0136] Figures 1 to 8The described embodiments may be stored in a computer-readable storage medium and executed by a computing system including at least one processor and a memory. Examples of computer-readable media include: magnetic media, such as hard disks, floppy disks, and magnetic tapes; optical media, such as CD ROM disks and DVDs; magneto-optical media, such as floppy disks; and hardware devices specifically configured to store and execute program instructions, such as read-only memory (ROM), random access memory (RAM), flash memory, etc. Examples of program instructions include machine code such as produced by a compiler and high-level code that can be executed by a computer using an interpreter, etc.

[0137] The above description of the example embodiments is provided for illustration, and those skilled in the art will appreciate that various changes and modifications may be made without changing the technical concepts and essential features of the example embodiments.

[0138] The scope of the inventive concept is defined by the appended claims and their equivalents, rather than by the detailed description of the exemplary embodiments. It should be understood that all modifications and embodiments that come within the meaning and scope of the claims and their equivalents are included within the scope of the inventive concept.

Claims

1. An output voltage controller, comprising: a virtual resistance calculator configured to calculate a virtual resistance value according to an output voltage measurement value and the output current measurement value when the output current measurement value exceeds a predetermined current limit value; a signal subtractor configured to generate a subtraction signal based on the calculated virtual resistance value and the voltage command value; as well as A controller is configured to generate a signal for controlling an output voltage based on the subtraction signal generated by the signal subtractor.

2. The output voltage controller according to claim 1, wherein: The virtual resistance calculator calculates a predicted load resistance value based on the output voltage measurement value and the output current measurement value, and compares the calculated predicted load resistance value with the load resistance value at the maximum load, and When the load resistance value at the maximum load is greater than the calculated predicted load resistance value, the virtual resistance calculator calculates the virtual resistance value according to the load resistance value at the maximum load and the predicted load resistance value, and When the load resistance value at the maximum load is smaller than the calculated predicted load resistance value, the virtual resistance value is the same as the calculated predicted load resistance value.

3. The output voltage controller according to claim 1, wherein: The output voltage controller calculates a voltage drop of a virtual resistor according to the output current measurement value, the current limit value and the virtual resistor value, and The signal subtractor comprises: a first signal subtractor configured to generate a second output voltage command value according to the calculated voltage drop of the virtual resistor and the first output voltage command value; and A second signal subtractor is configured to generate an error value according to the second output voltage command value and the output voltage measurement value.

4. The output voltage controller according to claim 1, wherein: The controller is a proportional resonant controller defined by the following equation 1: Equation 1 Where K P is the proportional gain, K i is the resonant gain, ω c is the cutoff frequency and ω c is the resonant frequency.

5. The output voltage controller according to claim 1, wherein: The controller controls the output voltage by adjusting a pulse width modulation duty cycle value, namely a PWM duty cycle value.

6. A device for limiting output current in a power supply system, comprising: An output voltage controller, comprising: a virtual resistance calculator configured to calculate a virtual resistance value based on an output voltage measurement value and an output current measurement value; a signal subtractor configured to generate a subtraction signal based on the virtual resistance value and a voltage command value; and a controller configured to generate a signal for controlling an output voltage based on the subtraction signal generated by the signal subtractor; and The pulse width modulation trip logic, PWM trip logic, is configured to control the gate driver in association with the signal from the output voltage controller, wherein, disabling the PWM trip logic when the output current measurement exceeds the current limit value, and enabling the PWM trip logic when the output current measurement does not exceed the current limit value, controlling a signal output from the gate driver based on a signal generated by the controller and a signal generated by the PWM trip logic, and The current delivered to the load is controlled by controlling the switching unit based on the signal output from the gate driver.

7. The device according to claim 6, wherein: The virtual resistance calculator calculates a predicted load resistance value based on the output voltage measurement value and the output current measurement value, compares the calculated predicted load resistance value with the load resistance value at the maximum load, and calculates the virtual resistance value based on the load resistance value at the maximum load and the calculated predicted load resistance value when the load resistance value at the maximum load is greater than the calculated predicted load resistance value, When the load resistance value at the maximum load is smaller than the calculated predicted load resistance value, the virtual resistance value is the same as the calculated predicted load resistance value.

8. The device according to claim 6, wherein: The output voltage controller calculates a voltage drop of a virtual resistor according to the output current measurement value, the current limit value and the virtual resistor value, and The signal subtractor comprises: a first signal subtractor configured to generate a second output voltage command value according to the calculated voltage drop of the virtual resistor and the first output voltage command value; and A second signal subtractor is configured to generate an error value according to the second output voltage command value and the output voltage measurement value.

9. The device according to claim 6, wherein: The signals output from the gate driver include a pulse width modulation signal, ie, a PWM signal, for controlling the U-phase output and a PWM signal for controlling the V-phase output.

10. The device according to claim 6, wherein: The predetermined current limit value is a maximum current value that the power supply system can supply.

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