TW201517471A - Method and apparatus of inrush current limitation - Google Patents

Abstract

The invention of apparatus of current limitation includes a power device which is connected with the power converter circuit and a controller which controls the power device. The control method of the current limitation apparatus is to control the power device in the linear region during start-up process in order to limit the inrush current and in the saturation region after start-up such that the loss can be significantly reduced.

Description

Surge current limiting device and method

The present invention relates to a current control device; and more particularly to a power device that utilizes the characteristics and controller of the power switch itself to improve conventional surge current control techniques and reduce its power loss.

The prior art is mainly composed of a resistive component and a mechanical relay connected in parallel, which is connected in series with the input AC power source, so that the resistive component can generate current suppression effect, and then the mechanical relay is turned on to reduce the power. loss. Because of its simple structure and low cost, it is widely used. However, the life of the relay is not as long as the average electronic component. In addition to the risk of failure, the relay itself still consumes a certain amount of power, so the overall power loss can be limited.

The prior art 2 is mainly composed of a resistive component and a controlled rectifier in parallel, so that the resistive component can generate current suppression effect, and then the controlled rectifier is turned on to reduce the loss of the work resistive component. However, the conduction loss of its controlled rectifier is not as small as that of a general rectifier, and its power loss can be reduced, which limits the overall efficiency.

Known surge current limiting devices, due to the non-ideal characteristics of the components and non-ideal circuit design, in addition to providing limited surge current suppression, their power consumption is still large, and when the input voltage is abnormally elevated, it cannot be protected. Components on the circuit. because Therefore, there is a need to develop a surge current limiting device that can further reduce the surge current, reduce power consumption, and protect the component when an abnormal voltage is input.

The surge current limiting circuit device of the present invention comprises: a power switch connected in series with the converter circuit and a controller for controlling the power switch. The controller's control method controls the power switch to operate in the linear region during the converter startup process to limit the surge current and operate in the saturation region to reduce losses when the converter is started.

Please refer to the first figure. The first figure is a schematic diagram of the circuit structure of the power supply of the conventional surge current limiter. Generally, the surge current limiting device 10, the input voltage conversion unit 11, and the storage capacitor 101 are mainly used. And the output voltage conversion unit 12, wherein the surge current limiting device 10 functions as a device for limiting the current before the voltage input is instantaneous and the storage capacitor 101 has not established any voltage. The input voltage conversion unit 11 converts the input AC or DC boost into a first DC voltage Vdc11 and stores it in the storage capacitor 101. The output voltage conversion unit 12 connected in series with the voltage conversion unit 11 converts the high voltage DC voltage Vdc11 outputted by the voltage conversion unit 11 into a required second DC voltage Vdc12 such as 5V, 12V, 48Vc or a second AC voltage. Vac12 such as 1500Vac, 3000Vac or other specifications voltage.

The architecture adopted by the surge current limiting device 10 is currently used in a switching power supply device by using a relay or a silicon controlled rectifier in parallel as a current limiting device such as a negative temperature coefficient resistor. (NTC) or a fixed resistor. Relays are widely used because of their simple control and low cost. In order to achieve the effect of suppressing the surge current, The relay or the controlled rectifier is turned off during the input voltage set-up, so that current flows through the current limiting resistor, thereby limiting the surge current. When the first DC voltage Vdc11 is established, it is turned into an on state, so that the power consumption above the current limiting resistor is lowered. In addition, the control action of the controlled rectifier is similar to that of the relay, but its switching speed is faster than that of the relay, which can replace the function of some bridge rectifiers.

Please refer to the second figure. The second figure is a schematic diagram of the input voltage and the surge current in the instant of the prior art. When the first DC voltage Vdc11 is established, its highest surge current is controlled by the current limiting resistor. The larger the resistance is, the lower the instantaneous current is. However, the instantaneous power is also larger, so the component size also needs to be increased. The undercurrent current size is about 30A. In addition, both the relay and the controlled rectifier have non-ideal characteristics. The on-resistance of the relay and the forward voltage drop of the controlled rectifier are higher than that of the normal diode, so that the current during normal operation still generates unnecessary power loss. Therefore, under the conventional architecture, the power loss can reach about 2W.

The reason is that this creator feels the improvement of the above-mentioned lacks. He is devoted to research and coordination with the theory. He proposes a systematic and integrated way of thinking based on line analysis, which can greatly reduce the surge current and improve the overall without increasing the component size. The creation of efficiency.

The purpose of the present invention is to improve the surge current problem of the conventional switched power supply, improve system efficiency, and protect the line components when an abnormally high voltage is input.

The third figure is an exchange power supply having the surge current limiting device of the present invention, comprising: an input voltage conversion unit, a storage capacitor, an output voltage conversion unit, a power switch, and a controller. At the same time depending on the system and specifications, The input voltage converter can use a power factor corrector or a voltage doubler rectifier, wherein the power factor corrects the power factor correction of the appliance and generates the function of the pre-regulated voltage Vdc31, and the voltage doubler rectification can be switched according to the input condition to achieve the voltage doubler rectification Vdc31.

The storage capacitor 301 is used to store the energy of the input voltage conversion unit and to provide an output voltage conversion unit. The output voltage conversion unit is configured to adjust and stably output the second DC Vdc32 or the second AC Vac32 according to the load condition by using the duty cycle adjustment or the frequency adjustment manner.

The power switch 312 utilizes power electronic switching characteristics to operate in a linear region of large impedance during power-on, a short-circuit region during normal operation after power-on, and an open circuit region for input of overvoltage protection. The use of its own low on-resistance characteristics and circuit design achieves the goal of reducing power consumption.

The controller 313 controls the power switch 312 to be in an open state before receiving the input voltage signal and not reaching the power-on voltage level. When the input voltage signal reaches the first reference voltage Vi51, a linear rising control voltage is generated, so that the power switch can operate in a high impedance region or a linear region, thereby greatly reducing the surge current to 2A. When the control voltage reaches a stable state, the power switch is fully turned on, because the design of the present invention causes the power loss generated by the normal operating voltage to be reduced by 1.5 W compared with the prior art. When the input voltage reaches the abnormal high voltage of Vi52, the control signal can switch its power back to the open state, and the input high voltage can be tolerated by the limiting device, so that all subsequent components can be protected.

The surge current controller control method of the present invention determines the current working state based on the input threshold voltage based on the input two threshold conditions, and the method is a repeatable loop control strategy. The two boundary value conditions are: the first critical value And a second critical value. The relationship between the two boundary values is that the second threshold is greater than the first threshold. Therefore, the two boundary value conditions can be divided into three state intervals, which are described as follows: First, if the first input voltage Vac1 or Vdc1 voltage level is stable less than the first threshold value, then an input undervoltage condition is entered. The voltage converter, the output voltage converter, and the power switch do not operate. However, if the first input voltage is stable greater than the first threshold but less than the second threshold, then it is determined that the normal input voltage interval is present, and the surge current limiting device control circuit generates a linear rising control waveform, so that the The power switch enters a linear range of high impedance. As the control waveform increases, the impedance decreases linearly, causing the charging current on the storage capacitor to exhibit a steady rising waveform. Finally, the limiting device reaches a fully conducting steady state. In this case, the input voltage converter can start to operate, and then the output voltage converter starts to operate.

However, if the input voltage continues to rise above the second threshold voltage, the active current limiting device controls the line to send a control signal to turn off the output voltage converter, then turns off the input voltage converter, and finally turns off the power switch. As a result, the input high voltage will not cause irreversible damage to the storage capacitor or the electronic components on it.

The surge current limiting device and method with the surge current limiting function of the invention can effectively reduce the power consumption under normal operation. At the same time, under different input voltage conditions, the operation state of the input voltage converter, the output voltage converter and the surge current limiting switch can be controlled, thereby effectively protecting the components thereon from damage caused by excessive input voltage. . Moreover, since compared with the conventional surge current control circuit, the present invention can reduce the current flowing through the limiting device during normal operation, thereby reducing the overall machine loss and improving the efficiency.

The detailed description of the present invention and the accompanying drawings are intended to provide a further understanding of the invention.

Please refer to the third figure. The third figure is the third embodiment of the switching power supply having the surge current limiting device 31 of the present invention, comprising: an input voltage converter 30, an output voltage converting unit 311, and an electric power. The switch 312 and a controller 313. The input voltage converter further includes a filter. The output voltage converter 311 can use a DC output converter or an AC output voltage converter according to the specifications. The technical features of the surge current limiting device 3 having the surge current high efficiency of the present invention will be described in detail below.

An AC voltage Vac3 or a DC voltage Vdc0 is transmitted to the input voltage converter 30 for power conversion, power factor correction, pre-adjustment of voltage or input voltage doubler, and then outputs a first DC voltage Vdc31. The output voltage conversion unit converts the Vdc 31 into a desired second DC voltage Vdc32 or a second AC voltage Vac32 after it is established. The output voltage converter adjusts the switching frequency or duty cycle of the power crystal to stabilize the second DC voltage Vdc32 or the second AC voltage Vac32. The power switch control circuit 313 detects the input voltage condition and utilizes a hysteresis comparison mechanism to control the circuit operation of its power switch 312.

The fourth figure is a specific embodiment of the controller of the surge current limiting device 31 of the present invention. The controller 313 can define a working interval by setting a boundary condition, and the power supply operates in three sections of input low voltage, normal voltage or excessive voltage. The hysteresis comparator 41 in the control unit of the surge current limiting device is used to set the two reference voltages to divide the input voltage into three intervals, control the working state of the power switch 312 in three intervals, and adopt hysteresis comparison control. Concept avoidance Avoid mistakes and act as a benchmark for the next stage of the signal.

The fifth figure is a schematic diagram of voltage and timing of the surge current limiting control method of the present invention. The surge current controller compares the input voltage with reference to the input voltage, and can set a two-stage input voltage threshold value in the controller, which is an input voltage first threshold Vi51 and a second threshold Vi52. The two thresholds divide the input voltage into three intervals, which are described as follows:

(1) When t0 < t < t1 When the input voltage is lower than the first threshold voltage Vi51, the power switch operating state is off, and neither the input voltage converter nor the output voltage converter operates.

(2) t1 < t < t2 When the input voltage is higher than the first threshold Vi51 but lower than the second threshold Vi52, the hysteresis comparator in the surge current controller outputs a signal, so that the power switch linear region control The line starts to operate, and the control region of the power switch is controlled in the high impedance region by a linear rising control voltage, and continues to slowly drop, so that the input current can charge the storage capacitor with a slow charging current. The control voltage rise slope can be calculated from the characteristics of the power switching elements to which the present invention is coupled so that the crystal can safely operate in a stable large impedance region for a controlled period of time.

(3) t2 < t < t3 When the voltage of the surge current controller continues to rise to a preset saturation voltage, it can be controlled by time or voltage, and its input voltage converter or voltage doubler is started to operate, and its first DC voltage is to be operated. When the setup is completed, the output voltage converter starts to operate to output the voltage required by the system.

(4) t3<t<t4 When the input voltage continues to rise and exceeds the second threshold voltage Vi52, the power switch overvoltage may be damaged at this time. The voltage detection 40 of the present invention detects the signal and notifies the power switch. Off, input and output voltage turn The converter stops operating, so that the components are protected from excessive input voltage damage.

In the present invention, as long as the appropriate component line parameter design is adopted, an ultra-low input surge current can be achieved, thereby avoiding damage caused by excessive input surge current, such as instantaneous high power output demand of the input voltage source, and safety circuit breaker. False triggering, excessive transient current level requirements of the input components of the power supply, etc.

What is more, the present invention utilizes voltage detection technology to protect components from excessive input voltages, and its functions are beyond the reach of conventional techniques.

In summary, this creation is an indispensable invention creation device and method, which is highly industrial, novel, and progressive. It is fully in line with the requirements for invention patent applications, and applications are filed in accordance with the Patent Law. Check and approve the patent in this case to protect the rights of the creators.

However, the above descriptions are only for the detailed description and drawings of the preferred embodiments of the present invention, and thus the scope of the patents of the present invention is not limited thereto, so the equivalent variations of the present specification and the drawings are used. All of the same are included in the scope of this creation. Anyone who is familiar with the art in the field of the invention can easily think of changes or modifications that can be covered in the following patent scope of the present invention.

The first picture: a conventional switching power supply with surge current suppression

10‧‧‧ Surge current limiting device

11‧‧‧Input voltage conversion unit

12‧‧‧Output voltage conversion unit

101‧‧‧First DC storage capacitor

Vac1‧‧‧ AC input voltage

Vdc1‧‧‧DC input voltage

Vdc11‧‧‧ first DC voltage

Vdc12‧‧‧second DC voltage

Vac12‧‧‧second AC voltage

Figure 2: Schematic diagram of the input voltage and surge current of the conventional technology in the instant of power-on

Vin‧‧‧Input voltage

Iin‧‧‧ input current

Third diagram: Switching power supply of the surge current limiting device of the present invention

30‧‧‧Input voltage converter

311‧‧‧Output voltage converter

31‧‧‧ Surge current limiting device

312‧‧‧Power switch

313‧‧‧ Controller

Vac3‧‧‧ AC input voltage

Vdc0‧‧‧DC input voltage

Vdc31‧‧‧ first DC voltage

Vdc32‧‧‧second DC voltage

Vac32‧‧‧second AC voltage

Fourth figure: controller specific embodiment of surge current limiting device

40‧‧‧Voltage detection

41‧‧‧Magnetic hysteresis comparator

42‧‧‧Linear Linear Voltage Control Generator

Figure 5: Voltage and timing diagram of the surge current limiting control method

Vi51‧‧‧First threshold voltage

Vi52‧‧‧second threshold voltage

The first figure is a schematic diagram of the circuit structure of the conventional surge current limiting device switching power supply; the second figure is a schematic diagram of the input voltage and the surge current of the prior art in the instant of starting; the third figure is the surge of the present invention A schematic diagram of a current limiting device; a fourth embodiment is a specific embodiment of a power switch control unit according to the present invention; The fifth figure is a schematic diagram of the timing and reference voltage of the control method of the power switch control unit proposed by the present invention;

30‧‧‧AC/DC converters: voltage doubler rectification, power factor corrector or other input voltage converter

31‧‧‧ Surge current limiting device

312‧‧‧Power switch: such as field effect transistor, IGBT and other components

313‧‧‧ Controller: Generate a control voltage to control the power switch

311‧‧‧Output voltage converter

Claims (7)

A surge current limiting device includes: a power switch connected in series with a converter circuit, which operates in a linear region during a converter startup process to limit a surge current and operates in a saturation region when the converter is started up Reduce losses. A controller is configured to detect a startup process for the input voltage state to control the power switch to operate in the linear region during the converter startup process and to operate in the saturation region when the converter startup is completed. The surge current limiting device of claim 1, wherein the controller comprises a voltage detection, a hysteresis comparator and a linear region linear voltage control generator. A method for controlling a surge current limiting device is to determine at least two voltage margin conditions to determine a current input state based on detecting an input voltage, the method comprising the steps of: a. determining a voltage level of the input voltage, b. The active surge current suppression switch operates in the conduction zone, the cutoff zone or the linear zone and c. causes the input voltage converter and the output voltage converter to operate or shut down. The method for controlling a surge current limiting device according to claim 3, wherein the two threshold voltage values are set, and the relationship is that the second threshold voltage value is greater than the first threshold voltage value. The method for controlling a surge current limiting device according to the third aspect of the patent application, wherein the step a. determines that the input voltage is lower than the first threshold voltage value, and the step b. causes the input voltage converter and the output voltage converter And the active surge current suppression switch does not operate. The method for controlling a surge current limiting device according to the third aspect of the patent application, wherein a. determining that the input voltage is between the first threshold voltage value and the second margin voltage, then the step b. The spur current suppression switch operates in the linear region, and when the active spur current suppression switch enters the all-on state, the input voltage converter and the output voltage converter are sequentially operated. The method for controlling a surge current limiting device according to the third aspect of the patent application, wherein a. the step of determining that the input voltage is higher than the second threshold voltage value, the step b. the input voltage converter, the output voltage converter And the active surge current suppression switch does not operate to protect its components.