Power control system and driving method therefor

Abstract

A power control system is disclosed. More specifically, the present invention relates to a power control system and a driving method therefor, the system protecting an SSPC load end system that includes a semiconductor device used in a power distribution system for supplying power. According to an embodiment of the present invention, when a power-on signal is input into a power control system for a semiconductor, the magnitude of a current is sensed through an internal current sensor so as to monitor an inrush current, and, when an overcurrent occurs, the size of an output capacitor is predicted through an MCU, and the next inrush current is predicted so as to proceed in a normal operation mode or a retry mode, thereby preventing damage to a semiconductor device due to the occurrence of the overcurrent and ensuring driving stability of the entire system.

Description

Power control system and method of driving the same

[0001] The present invention relates to a power control system, and more particularly to a power control system that protects a load connected to a power supply system including a semiconductor switch, and a method for driving the same.

[0002] Currently, advancements in semiconductor device technology are enabling the miniaturization of semiconductor components and steadily increasing their reliability. Consequently, mechanical components, which have been widely used across various industries, are gradually being replaced by semiconductor devices that are smaller, lighter, and easier to control.

[0003] Recently, there has been a noticeable shift in the field of protection circuits, where mechanical relays and magnetic circuit breakers were used in power distribution systems, toward the application of Solid State Relays (SSRs) or Solid State Power Controllers (SSPCs), which can ensure high reliability and are easy to maintain.

[0004] The aforementioned SSR refers to a switch that controls the flow of power in an on / off manner using semiconductor devices, and the SSPC is a device that adds a control function to the function of an SSR, characterized by its ability to actively change the on / off operation conditions of the switch according to user commands.

[0005] In the case of semiconductor switch products used as such power breakers, the contacts between the input power terminal and the load terminal are controlled in an open or closed manner. When the two contacts are initially connected, an inrush current with a large peak value flows to charge the input capacitor of the load terminal. The magnitude of this inrush current is determined by the influence of the load-side input capacitor (CLoad), parasitic resistance (RESR), and parasitic inductance (LESL).

[0006] Here, the magnitude of the inrush current increases as the size of the load-side input capacitor increases, or as the size of the parasitic inductance and parasitic resistance decreases. Generally, as the load-side input capacitor has a much larger value than the parasitic inductance, a high inrush current occurs during the circuit breaker closing operation.

[0007] If the magnitude of the inrush current increases beyond the allowable current of the semiconductor device, it causes failure of the semiconductor switch, and if the magnitude of the inrush current increases beyond the allowable current of the circuit breaker, the circuit breaker detects this and causes a malfunction in opening the contacts.

[0008] To prevent damage to semiconductor devices caused by such inrush current, a widely used conventional method is the pre-charging circuit.

[0009] FIG. 1 is an equivalent circuit diagram showing the RLC components of a switch included in a conventional power control system. Referring to FIG. 1, the existing charging circuit configuration is connected in parallel with a circuit breaker and adds an additional circuit for only the initial inrush current, thereby providing an initial charging resistor (R Aux ) and initial charging switch element (SW Aux ) is used additionally. In this case, a switch (SW) applied to the additional circuit is used. Aux ) operates and closes before the semiconductor switches (SSPC, SSR) at initial startup, thereby connecting the power supply and the load. As a result, a current path is created between the power supply and the load through the initial charging circuit, and the magnitude of the inrush current can be limited as the initial charging resistor acts to suppress the rise in the initial current. However, in this method, the initial charging switch (SW Aux Not only is an additional control signal required for driving, but a driving circuit for the switch is also needed, which ultimately causes an increase in the volume and weight of the system.

[0010] Another method is the retry method, which sends a control signal to close the semiconductor circuit breaker when it opens due to an inrush current. The retry method is a method in which, even when the semiconductor circuit breaker opens (OPEN) due to an overcurrent detected by a current sensor, the initial operation of the semiconductor circuit breaker is judged to be normal operation due to the inrush current, and the contacts are repeatedly closed again.

[0011] According to this method, as the load-side capacitor is gradually charged during the process of repeatedly closing the switch contacts, the charging voltage of the output capacitor increases, thereby reducing the magnitude of the inrush current. This has the advantage of preventing damage from the initial inrush current without the need for additional component configuration.

[0012] However, there is a limitation in that if the tripping operation of the semiconductor switch does not occur very quickly, damage to the semiconductor device due to overcurrent accumulates during the retry process, eventually leading to the destruction of the semiconductor circuit breaker. Additionally, in the retry method, in order to ignore the effects of inrush current, the circuit breaker contacts are repeatedly closed even when an overcurrent warning is detected, ignoring the warning. Due to this fixed repetitive operation, a problem arises where the fault is not recognized even when an actual system failure occurs.

[0013] Prior Art: Korean Published Patent Application No. 10-2021-0095453 (Publication Date: August 2, 2021)

[0014] The present invention has been devised to solve the aforementioned problems, and has the objective of preventing device damage caused by inrush current in a power control system for semiconductors, thereby protecting the load-side system of an SSPC or SSR.

[0015] To solve the aforementioned problem, a power control system according to an embodiment of the present invention may include a switch made of a semiconductor device connected between an input terminal and an output terminal that supplies power, a driving circuit that turns the switch on or off, a current sensor that senses a current flowing through the switch, and an MCU that receives a sensing result from the current sensor, enters a first driving mode if no overcurrent is detected, switches the switch to an off state, and enters a second driving mode if an overcurrent is detected.

[0016] The first driving mode above is a normal driving mode, and the second driving mode above may be a retry driving mode that restarts by turning off the switch.

[0017] When the MCU enters a second driving mode based on overcurrent detection, after the switch is turned off, it can calculate the capacitance of the output capacitor based on the magnitude of the detected inrush current and predict the magnitude of the next inrush current.

[0018] After entering the second driving mode, the MCU may maintain the second driving mode if the overcurrent is smaller than or equal to the predicted next inrush current, and generate a fault signal and stop driving if the overcurrent is larger than the predicted next inrush current.

[0019] The above inrush current {i(t)} is given by the following mathematical formula,

[0020]

[0021]

[0022] It can satisfy.

[0023] The above switch may be a semiconductor device among an IGBT and a MOSFET made of SiC or GaN.

[0024] In addition, to solve the aforementioned problem, a driving method of a power control system according to an embodiment of the present invention may include a power-on step, a step of turning on a switch by controlling a driving circuit, a step of sensing a current flowing through a switch through a current sensor, a step of entering a first driving mode if no overcurrent is detected as a result of current sensing, and a step of turning off the switch and entering a second driving mode if an overcurrent is detected to calculate the capacity of an output capacitor and predict the magnitude of the next inrush current, and a step of, after entering the second driving mode, turning on the switch to detect the current flowing through the switch and, if no overcurrent is detected, switching to the first driving mode, and if an overcurrent is detected, turning off the switch and re-entering the second driving mode.

[0025] After entering the second driving mode, the switch is turned on to detect the current flowing through the switch, and if no overcurrent is detected, the system switches to the first driving mode. If an overcurrent is detected, the switch is turned off and the system re-enters the second driving mode. After the second driving mode, when an overcurrent is detected, if the detected overcurrent is smaller than or equal to the predicted next inrush current, the current mode is maintained, and if the detected overcurrent is larger than the predicted next inrush current, a fault signal is generated and the system stops driving.

[0026] According to an embodiment of the present invention, when a power-on signal is input to a power control system for semiconductors, the magnitude of the current is sensed through an internal current sensor to monitor the inrush current, and when an overcurrent occurs, the magnitude of the output capacitor is predicted through the MCU and the next inrush current is predicted to proceed to a normal operation mode or a retry mode, thereby protecting the load-side system of the SSPC or SSR from the occurrence of an overcurrent and ensuring the operational stability of the entire system.

[0027] Figure 1 is a diagram showing the RLC components of a switch included in a conventional power control system as an equivalent circuit diagram.

[0028] FIG. 2 is a block diagram showing the structure of a power control system according to an embodiment of the present invention.

[0029] FIG. 3 is a diagram showing an RLC equivalent circuit diagram for a circuit including a switch included in a power control system according to an embodiment of the present invention.

[0030] Figure 4 is a graph showing the current and voltage magnitudes of the load capacitance according to the connection structure of the switch of a power control system according to an embodiment of the present invention.

[0031] FIG. 5 is a graph showing the magnitude of the output voltage of the inrush current in the second driving mode of a power control system according to an embodiment of the present invention.

[0032] FIG. 6 is a flowchart illustrating a method of driving a power control system according to an embodiment of the present invention.

[0033] The present invention as described above will be explained in detail through the attached drawings and embodiments.

[0034] It should be noted that the technical terms used in this invention are used merely to describe specific embodiments and are not intended to limit the invention. Furthermore, unless specifically defined otherwise in this invention, the technical terms used in this invention should be interpreted in the sense generally understood by those skilled in the art to which this invention pertains, and should not be interpreted in an overly broad or overly narrow sense. Additionally, if a technical term used in this invention is an incorrect technical term that fails to accurately express the concept of the invention, it should be replaced with a technical term that can be correctly understood by those skilled in the art. Moreover, general terms used in this invention should be interpreted according to their prior definitions or the context, and should not be interpreted in an overly narrow sense.

[0035] Furthermore, singular expressions used in the present invention include plural expressions unless the context clearly indicates otherwise. In the present invention, terms such as "composed of" or "comprising" should not be interpreted as necessarily including all of the various components or steps described in the invention, and should be interpreted as meaning that some of the components or steps may not be included, or that additional components or steps may be included.

[0036] Additionally, terms including ordinal numbers, such as first, second, etc., used in the present invention may be used to describe components, but the components should not be limited by these terms. The terms are used solely for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be named the second component, and similarly, the second component may be named the first component.

[0037] Hereinafter, a power control system and a driving method according to an embodiment of the present invention will be described in detail with reference to the drawings.

[0038] FIG. 2 is a block diagram showing the structure of a power control system according to an embodiment of the present invention.

[0039] A power control system according to an embodiment of the present invention is characterized by a structure that can prevent damage to a semiconductor switch caused by inrush current while minimizing the burden on additional components.

[0040] To this end, the power control system of the present invention is characterized by determining whether the current flowing through the switch is an overcurrent using a microcontroller unit (MCU) mounted on a known semiconductor circuit breaker or semiconductor power controller to determine the driving mode, and predicting the capacitance of the output capacitor on the loop formed by the switch, calculating the magnitude of the inrush current using the predicted information, and then effectively determining and performing the number of retry cycles.

[0041] Referring to FIG. 2, a power control system (100) according to an embodiment of the present invention may include a switch (110) made of a semiconductor device connected between an input terminal and an output terminal that supplies power, a driving circuit (120) that turns the switch on or off, a current sensor (130) that senses a current flowing through the switch (110), and an MCU (140) that receives a sensing result from the current sensor (130), enters a first driving mode if no overcurrent is detected, switches the switch to an off state, and enters a second driving mode if an overcurrent is detected.

[0042] The switch (110) can be electrically connected between an input line to which power is supplied and an output line to which power is output to a load.

[0043] For such a switch (110), devices such as IGBTs and MOSFETs made of materials such as SiC and GaN can be used.

[0044] Silicon carbide (SiC) is a compound semiconductor material composed of silicon (Si) and carbon (C). It has excellent dielectric breakdown electric field strength that is 10 times that of Si and a band gap that is 3 times that of Si, and is used as a power control material because it allows for a wide range of control of the P-type and N-type required for device fabrication.

[0045] Gallium nitride (GaN) is a III-V compound semiconductor that has the advantage of having a high breakdown voltage and excellent high-temperature stability compared to semiconductor devices made of other compound semiconductor materials such as GaAs. Accordingly, semiconductor devices made of GaN are widely used in devices that use high power or are prone to exposure to high temperatures.

[0046] Furthermore, the IGBT fabricated from the aforementioned materials stands for Insulated Gate Bipolar Transistor. It is a semiconductor device for high-power driving with high-speed switching that combines a MOSFET (Metal Oxide Silicon Field Effect Transistor)—that is, a metal oxide silicon field effect transistor—with a general bipolar transistor, utilizing the strengths of both devices; it is primarily used for power control.

[0047] In addition, MOSFETs have the advantage of enabling high-speed switching because, as voltage devices, driving current does not flow through the insulating gate, but on / off operation between the drain and source can be performed by forming an electric field through the voltage applied to the gate.

[0048] The driving circuit (120) is electrically connected to the gate of the switch (110) to control the on / off operation. Under the control of the MCU (140), the driving circuit (120) turns on the switch (110) in a normal driving mode to supply power to the load, and in a situation where an overcurrent exceeding the allowable flows through the switch (110), it operates in a retry mode to switch the switch (110) to an off state to prevent damage to the load connected to the system.

[0049] A current sensor (130) can be electrically connected to the input and output terminals of the switch (110) and can detect the current flowing through the switch and provide it to the MCU (140). As such a current sensor (130), a Hall effect sensor that generates a Hall voltage proportional to the magnetic field formed around each line-out conductor due to the current flowing through the conductor may be used, but is not limited thereto.

[0050] For example, according to an embodiment of the present invention, the MCU (140) described below is programmed to monitor the current flowing through the switch (110) and to diagnose that an overcurrent is flowing, and the current sensor (130) can detect and measure the line current flowing from the line-out terminal, and the results of such Hall effect measurements can be performed in real time and, if necessary, amplified and provided to the MCU (140).

[0051] The MCU (140) can determine whether there is an overcurrent based on the magnitude of the current measured by the current sensor (130) and determine the operating mode of the system (100). This MCU (140) can be replaced with any type of device having the same computing power.

[0052] In detail, when the power of the system (100) is turned on, the MCU (140) controls the driving circuit (120) to switch the switch (110) to the ON state so that power is supplied to the load, and the current sensor (130) can sense the current flowing through the switch (110) and transmit it to the MCU (140), thereby allowing the MCU (140) to monitor the magnitude of the current. At this time, the MCU (140) can store the monitoring result in a memory device mounted on the system (100).

[0053] Then, the MCU (140) monitors the initial current for a certain period while the switch (110) is on, and when the current is monitored to be within the normal range, it enters the first driving mode, that is, the normal driving mode.

[0054] On the other hand, if an overcurrent is detected, the MCU (140) can control the driving circuit (120) to switch the switch (110) to the off state. Subsequently, the MCU (140) can calculate the size of the output capacitor, i.e., the load capacitance, according to the circuit characteristics of the power control system (100) described later.

[0055] FIG. 3 is a diagram showing an RLC equivalent circuit diagram for a circuit including a switch included in a power control system according to an embodiment of the present invention.

[0056] In particular, a semiconductor circuit breaker (SSR) or semiconductor power controller (SSPC) that uses a semiconductor element as a switch, such as the power control system (100) of the present invention, can be viewed as an equivalent circuit to an RLC series resonant circuit connected to a DC power source as in FIG. 3 when the input terminal and the output terminal are connected according to operation.

[0057] In the case of the aforementioned RLC series resonant circuit, the magnitude of the current flowing from the power supply is determined by the sizes of the inductor (L), capacitor (C), and resistor (R). The current flowing through the RLC series resonant circuit is equal to the current flowing through the capacitor, and the current flowing can be calculated through the relationship between the voltage and current in the capacitor. If the voltage {Vo(t)} across the capacitor in Fig. 3 is calculated, it is given by the following Equation 1.

[0058]

[0059]

[0060] Here, C is the output capacitance, V s is the power supply voltage, V0(t) is the voltage applied to the output capacitance, and ω is ' ', Q is ' ' am.

[0061] In the above mathematical equation 1, differentiating the capacitor voltage and multiplying by the capacitance yields the current flowing through the capacitor, i.e., the current of the RLC series resonant circuit, and this current becomes the inrush current. Accordingly, when organized into an equation based on the current {i(t)} and the capacitor voltage {Vo(t)}, it is as shown in mathematical equation 2 below.

[0062]

[0063]

[0064]

[0065] According to the above mathematical formula 2, when the parasitic inductance (L) and parasitic resistance (R) components are fixed, the load capacitance (C o It can be seen that the magnitude of the inrush current increases as the size of ) increases.

[0066] FIG. 4 shows the load capacitance (C) according to the connection structure of the switch of a power control system according to an embodiment of the present invention. oAs a graph showing the magnitudes of the current and voltage of ), referring to FIG. 4, the inrush current (a) and output voltage (b) according to the size of the output capacitor are shown, and the load capacitance (C o It can be observed that the waveforms of the inrush current and output voltage differ depending on the magnitude of ).

[0067] In addition, FIG. 5 is a graph showing the magnitude of the output voltage of the inrush current in the second driving mode of the power control system according to an embodiment of the present invention.

[0068] Referring to Figure 5, the inrush current and output voltage fluctuations are shown when entering the second driving mode, i.e., the retry operation. It can be seen that during retry driving, the magnitude and slope of the inrush current vary depending on the size of the output capacitor.

[0069] Generally, parasitic inductance and parasitic resistance components are known to be very small values ​​and are fixed at specific values ​​when the system is configured. Therefore, the magnitude of the load capacitance can be calculated by measuring the inrush current and output voltage, and based on the values ​​obtained in this way, the magnitude of the inrush current during retry driving can be predicted.

[0070] In particular, according to the aforementioned retry drive, the switch-on and off states are repeatedly alternately driven so that the output capacitor is gradually charged, and as the charging voltage of the output capacitor increases, the magnitude of the inrush current decreases, thereby significantly reducing the risk of device damage caused by the initial inrush current.

[0071] Next, the MCU (140) can predict the magnitude of the next inrush current, and if no overcurrent is detected, enter normal driving mode, and if an overcurrent is detected, re-enter retry driving mode and calculate the next inrush current at the current time.

[0072] At this time, if the measured overcurrent is greater than the next inrush current calculated at this time, the MCU (140) stops the operation of the system and generates a fault signal so that the user can recognize the current situation, as the possibility of damage to the semiconductor device increases.

[0073] Hereinafter, a method for driving a power control system according to an embodiment of the present invention will be described in detail with reference to the drawings.

[0074] FIG. 6 is a flowchart illustrating a method of driving a power control system according to an embodiment of the present invention. In the following description, the entity executing each step is the MCU of the power control system of the present invention, except where otherwise noted.

[0075] Referring to FIG. 6, according to the driving method of the power control system of the present invention, the power control system first starts to operate upon power-on, and the MCU controls the driving circuit to turn on the switch (S100).

[0076] Accordingly, the switch is turned on and power is supplied, and the current sensor senses the current flowing through the switch and provides the sensing result to the MCU in real time (S110).

[0077] Based on the current sensing result input through the above S110 step, the MCU determines the driving mode (S120), and if no overcurrent is detected, it enters the first driving mode, which is the normal driving mode (S130), thereby supplying power to the load normally.

[0078] In addition, if an overcurrent is detected based on the judgment result of step S120, the MCU controls the driving circuit to turn the switch off (S140), and calculates the capacitance of the output capacitor according to the aforementioned mathematical formulas 1 and 2 to predict the magnitude of the next inrush current (S150).

[0079] Next, the MCU enters the second driving mode, which is the retry driving mode (S160).

[0080] Upon entering the second driving mode, the MCU turns on the switch to detect the current flowing through the switch (S170), and if no overcurrent is detected, switches to the first driving mode (S130).

[0081] In addition, when detecting an overcurrent in step S170, the magnitude of the measured overcurrent is compared with the magnitude of the next inrush current predicted in step S150 (S180), and if the currently measured overcurrent is less than or equal to the predicted next inrush current, the process proceeds to step S150 to predict the next inrush current and re-enters the second driving mode (S160).

[0082] And, if the overcurrent measured in step S180 is greater than the next inrush current, the MCU generates a fault signal for the overcurrent so that the user can recognize that the operation has stopped.

[0083] Although many details are described in detail in the above description, this should be interpreted as an example of a preferred embodiment rather than as a limitation to the scope of the invention. Accordingly, the invention should not be determined by the described embodiment, but by the claims and equivalents thereof.

Claims

1. A switch composed of a semiconductor device connected between an input terminal and an output terminal that supply power; A driving circuit that turns the above switch on or off; A current sensor that senses the current flowing through the above switch; and An MCU that receives a sensing result from the above current sensor, enters a first driving mode if no overcurrent is detected, switches the above switch to an off state, and enters a second driving mode if an overcurrent is detected. A power control system including 2. In Paragraph 1, The above first driving mode is a normal driving mode, and The above second driving mode is, A power control system that is in a retry drive mode that restarts by turning off the above switch.

3. In Paragraph 2, The above MCU is A power control system that, when entering a second driving mode based on overcurrent detection, calculates the capacitance of an output capacitor based on the magnitude of the detected inrush current after the switch is turned off, and predicts the magnitude of the next inrush current.

4. In Paragraph 3, The above MCU is A power control system that, after entering a second driving mode, maintains the second driving mode when the magnitude of the overcurrent is less than or equal to the predicted next inrush current, and generates a fault signal and stops driving when the magnitude of the overcurrent is greater than the predicted next inrush current.

5. In Paragraph 3, The above inrush current {i(t)} is given by the following mathematical formula, A power control system satisfying (where C is the output capacitance, V s is the power supply voltage, V0(t) is the voltage applied to the load capacitor, and ω is ' ', Q is ' ' ).

6. In Paragraph 1, The above switch is, A power control system that is a semiconductor device among an IGBT and a MOSFET made of SiC or GaN.

7. A method for driving a power control system as described in Claim 1, Power on stage; Step of turning on the switch by controlling the driving circuit; A step of sensing the current flowing through the switch using a current sensor; A step of entering a first driving mode if no overcurrent is detected as a result of current sensing, and if an overcurrent is detected, turning off the switch and entering a second driving mode to calculate the capacitance of the output capacitor and predict the magnitude of the next inrush current; and After entering the second driving mode, the switch is turned on to detect the current flowing through the switch; if no overcurrent is detected, the system switches to the first driving mode, and if an overcurrent is detected, the switch is turned off and the system re-enters the second driving mode. A method of driving a power control system including 8. In Paragraph 7, After entering the second driving mode, the switch is turned on to detect the current flowing through the switch, and if no overcurrent is detected, the system switches to the first driving mode; if an overcurrent is detected, the switch is turned off and the system re-enters the second driving mode. A step in which, upon detecting overcurrent, if the detected overcurrent is less than or equal to the predicted next inrush current, the current mode is maintained, and if the detected overcurrent is greater than the predicted next inrush current, a fault signal is generated and operation is stopped. A method of driving a power control system including

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