Input overvoltage protection circuit for power supply device

Abstract

The present invention relates to an input overvoltage protection circuit for a power supply device, and discloses a power supply device, which includes a power converter, a protection circuit and a control circuit. The protection circuit includes an input terminal for receiving an input voltage, an output terminal for providing an output voltage to the power converter, a first switch device connected in a current path between the input terminal and the output terminal, and a second switch device connected at both ends of the first switch device. The control circuit is configured to sense the input voltage and the output voltage, disconnect the first switch device in response to the output voltage exceeding a first defined threshold and connect the second switch device to supply power to the power converter, and disconnect the second switch device in response to the input voltage exceeding a second defined threshold to cut off the connection between the power supply and the power converter. Other exemplary power supply devices and protection circuits are also disclosed.

Description

Technical Field

[0001] The invention relates to an input overvoltage protection circuit for a power supply device. Background Art

[0002] This section provides background information related to the present disclosure which is not necessarily prior art.

[0003] The power supply includes a power circuit that receives power from an input power source. Sometimes, the power supply includes a circuit coupled between the power source and the power circuit for providing input overvoltage protection and / or inrush current protection. For example, the power supply may include one or more electromechanical switching devices coupled between the power source and the power circuit to disconnect the power circuit during an overvoltage condition. In other examples, a resistor may be coupled across the electromechanical switching device to limit input inrush current from the power source. Summary of the invention

[0004] This section provides a general summary of the invention, and is not a comprehensive disclosure of its full scope or all of its features.

[0005] According to one aspect of the present invention, a power supply device includes a power converter, a protection circuit and a control circuit, wherein the protection circuit includes an input terminal connected to a power supply for receiving an input voltage, an output terminal connected to the power converter for providing an output voltage to the power converter, a first switching device connected in a current path between the input terminal and the output terminal, and a second switching device connected at both ends of the first switching device, wherein the first switching device can be controlled to be turned on during the startup of the power converter. The control circuit communicates with the first switching device and the second switching device. The control circuit is configured to sense the input voltage and the output voltage, disconnect the first switching device in response to the output voltage exceeding a first defined threshold and connect the second switching device to supply power to the power converter, and disconnect the second switching device in response to the input voltage exceeding a second defined threshold to cut off the connection between the power supply and the power converter.

[0006] According to another aspect of the present invention, a protection circuit for connecting between a power supply and a power converter to provide input overvoltage protection for the power converter is disclosed. The protection circuit includes an input terminal configured to be connected to the power supply for receiving an input voltage, an output terminal configured to be connected to the power converter for providing an output voltage to the power converter, a first switching device connected in a current path between the input terminal and the output terminal, a second switching device connected at both ends of the first switching device, and a control circuit. The first switching device can be controlled to be turned on during the startup of the power converter. The control circuit communicates with the first switching device and the second switching device. The control circuit is configured to sense the input voltage and the output voltage, disconnect the first switching device in response to the output voltage exceeding a first defined threshold and turn on the second switching device to supply power to the power converter, and disconnect the second switching device in response to the input voltage exceeding a second defined threshold to cut off the connection between the power supply and the power converter.

[0007] Concept 1: A power supply device, comprising:

[0008] Power converter;

[0009] a protection circuit comprising an input terminal coupled to a power source for receiving an input voltage, an output terminal coupled to the power converter for providing an output voltage to the power converter, a first transistor coupled in a current path between the input terminal and the output terminal, a relay coupled across the first transistor, and a second transistor coupled to the first transistor and configured to limit a current flowing through the first transistor, the first transistor being controllable to be turned on during startup of the power converter; and

[0010] A control circuit is in communication with the first transistor and the relay, the control circuit being configured to sense the input voltage and the output voltage, control the first transistor to be disconnected and control the relay to be connected to supply power to the power converter in response to the output voltage exceeding a first defined threshold, and control the relay to be disconnected to cut off the connection between the power source and the power converter in response to the input voltage exceeding a second defined threshold.

[0011] Concept 2: The power supply of Concept 1 wherein said first transistor is a self-biased MOSFET configured to turn on in response to said input voltage.

[0012] Concept 3: The power supply device of Concept 1 or 2, wherein the input voltage is an AC input voltage, the first defined threshold is a rated peak voltage of the AC input voltage, and the second defined threshold is a voltage of at least 120% of the rated peak voltage of the AC input voltage.

[0013] Concept 4: The power supply of any of Concepts 1-3, wherein said control circuit is configured to open said relay to disconnect said power source from said power converter in response to said input voltage exceeding said second defined threshold for a defined period of time.

[0014] Concept 5: The power supply apparatus of any of Concepts 1-4 wherein said defined time period is based on said second defined threshold.

[0015] Concept 6: The power supply device of any of Concepts 1-5, wherein said control circuit is configured to control said first transistor to turn on during startup of said power converter.

[0016] Concept 7: A power supply device comprising:

[0017] Power converter;

[0018] a protection circuit, the protection circuit comprising an input terminal coupled to a power source for receiving an input voltage, an output terminal coupled to the power converter for providing an output voltage to the power converter, a first switching device coupled in a current path between the input terminal and the output terminal, and a second switching device coupled across the first switching device, the first switching device being controllable to be turned on during startup of the power converter; and

[0019] A control circuit communicates with the first switching device and the second switching device, the control circuit being configured to sense the input voltage and the output voltage, disconnect the first switching device and connect the second switching device to supply power to the power converter in response to the output voltage exceeding a first defined threshold, and disconnect the second switching device to cut off the connection between the power source and the power converter in response to the input voltage exceeding a second defined threshold.

[0020] Concept 8: The power supply of Concept 7 wherein said first switching device is a self-biased switching device configured to turn on in response to said input voltage.

[0021] Concept 9: The power supply of Concept 7 or 8, wherein said control circuit is configured to turn on said first switching device during startup of said power converter.

[0022] Concept 10: The power supply device of any of Concepts 7-9, wherein the first switching device is a MOSFET, and wherein the second switching device is a relay.

[0023] Concept 11: A power supply as described in any of Concepts 7-10, wherein the input voltage is an AC input voltage, the first defined threshold is a rated peak voltage of the AC input voltage, and the second defined threshold is a voltage of at least 120% of the rated peak voltage of the AC input voltage.

[0024] Concept 12: The power supply of any of Concepts 7-11, wherein said control circuit is configured to disconnect said second switching device to disconnect said power source from said power converter in response to said input voltage exceeding said second defined threshold for a defined period of time.

[0025] Concept 13: The power supply of any of Concepts 7-12 further comprising at least one of a resistor and a third switching device coupled to the first switching device to limit current flowing through the first switching device.

[0026] Concept 14: The power supply of any of Concepts 7-13 wherein said power converter comprises a PFC circuit.

[0027] Concept 15: A protection circuit for connecting between a power supply and a power converter to provide input overvoltage protection for the power converter, the protection circuit comprising an input terminal configured to be connected to the power supply for receiving an input voltage, an output terminal configured to be connected to the power converter for providing an output voltage to the power converter, a first switching device connected in a current path between the input terminal and the output terminal, a second switching device connected across the first switching device, and a control circuit in communication with the first switching device and the second switching device, wherein the first switching device can be controlled to be turned on during startup of the power converter, the control circuit being configured to sense the input voltage and the output voltage, disconnect the first switching device and turn on the second switching device to supply power to the power converter in response to the output voltage exceeding a first defined threshold, and disconnect the second switching device to cut off the connection between the power supply and the power converter in response to the input voltage exceeding a second defined threshold.

[0028] Concept 16: The protection circuit of Concept 15 wherein said first switching device is a self-biased switching device configured to turn on in response to said input voltage.

[0029] Concept 17: The protection circuit of Concept 15 or 16 wherein said first switching device is a MOSFET and said second switching device is a relay.

[0030] Concept 18: The protection circuit of any of Concepts 15-17 wherein the input voltage is an AC input voltage, the first defined threshold is a rated peak voltage of the AC input voltage, and the second defined threshold is a voltage of at least 120% of the rated peak voltage of the AC input voltage.

[0031] Concept 19: The protection circuit of any of Concepts 15-18 wherein said control circuit is configured to disconnect said second switching device to disconnect said power source from said power converter in response to said input voltage exceeding said second defined threshold for a defined period of time.

[0032] Concept 20: The protection circuit of any of Concepts 15-19 further comprising at least one of a resistor and a third switching device coupled to the first switching device to limit current flowing through the first switching device.

[0033] From the description provided herein, other aspects and fields of application will become apparent. It should be understood that various aspects of the present invention can be implemented separately or in combination with one or more other aspects. It should also be understood that the description and specific examples herein are only for illustrative purposes and are not intended to limit the scope of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present invention.

[0035] Figure 1 is a block diagram of a protection circuit including two switching devices for cutting off connection of a power source to a power converter according to an exemplary embodiment of the present invention.

[0036] Figure 2 is a schematic diagram of a power supply device according to another exemplary embodiment, the power supply device including a power supply, a power converter, and a protection circuit having a MOSFET, a relay, and a control circuit for controlling the MOSFET and the relay to cut off the connection between the power supply and the power converter.

[0037] Figure 3 for Figure 2 A block diagram of a portion of the control circuit.

[0038] Figure 4 To include from Figure 2 Timing diagram of the waveforms of different parameters of the power supply device.

[0039] Figure 5 is a schematic diagram of a power supply device including a protection circuit according to another exemplary embodiment. The protection circuit has a switching device for limiting an input inrush current.

[0040] Figure 6 is a schematic diagram of a power supply device including a protection circuit according to yet another exemplary embodiment, the protection circuit having a resistor for limiting an input inrush current.

[0041] Figure 7 is a schematic diagram of a power supply device including a protection circuit having a switching device controlled by an auxiliary supply source according to another exemplary embodiment.

[0042] Figure 8 is a schematic diagram of a power supply device according to yet another exemplary embodiment, the power supply device comprising a power supply, a power converter, and a protection circuit in a low-side rail connected between the power supply and the power converter.

[0043] Fig. 9 is a schematic diagram of a power supply device according to another exemplary embodiment, the power supply device including a DC power supply, a DC / DC power converter, and a protection circuit for cutting off the connection between the DC power supply and the DC / DC power converter.

[0044] Corresponding reference numerals indicate corresponding (but not necessarily identical) components and / or features throughout the several views of the drawings. DETAILED DESCRIPTION

[0045] Exemplary embodiments are provided so that the present invention will be thorough and will fully convey the scope to those skilled in the art. A number of specific details, such as examples of specific components, devices and methods, are presented to provide a thorough understanding of embodiments of the present invention. It will be apparent to those skilled in the art that specific details need not be employed, that exemplary embodiments may be embodied in many different forms, and that both specific details and exemplary embodiments should not be construed as limiting the scope of the present invention. In some exemplary embodiments, well-known processes, well-known equipment structures, and well-known techniques are not described in detail.

[0046] The terms used herein are only for the purpose of describing specific exemplary embodiments and are not intended to be limited. As used herein, the singular forms "one" and "the" may also be intended to include plural forms unless the context clearly indicates otherwise. The terms "include", "comprise" and "have" are inclusive and therefore refer to the existence of stated features, integers, steps, operations, elements, and / or parts, but do not exclude the existence or addition of one or more other features, integers, steps, operations, elements, parts and / or their combinations. The method steps, processes and operations described herein should not be understood as necessarily requiring them to be performed in the specific order discussed or shown, unless specifically identified as an execution order. It will also be understood that additional or alternative steps may be adopted.

[0047] Although the terms "first", "second", "third", etc. can be used in this article to describe various elements, components, regions, layers and / or parts, these elements, components, regions, layers and / or parts should not be limited by these terms. These terms can only be used to distinguish an element, component, region, layer or part from another element, component, region, layer or part. Terms such as "first", "second" and other numerical terms do not imply order or sequence when used in this article unless the context has clear instructions. Therefore, the first element, first component, first area, first layer or first part discussed below can be referred to as the second element, second component, second area, second layer or second part, without departing from the teaching of exemplary embodiments.

[0048] For ease of description, spatially relative terms such as "inside", "outside", "below", "below", "lower", "above", "upper", etc. may be used herein to describe the relationship between an element or feature as shown in the figure and one or more other elements or features. In addition to the orientation shown in the figure, spatially relative terms may be intended to cover different orientations of the device in use or operation. For example, if the device in the figure is turned over, the element described as being "below" or "below" other elements or features will be oriented to be "above" the other elements or features. Thus, the exemplary term "below" can cover both above and below orientations. The device can be oriented otherwise (rotated 90 degrees or in other orientations) and the spatially relative descriptors used herein are understood accordingly.

[0049] Example embodiments will now be described more fully with reference to the accompanying drawings.

[0050] A protection circuit for connecting between a power source and a power converter to provide input overvoltage protection for the power converter according to an exemplary embodiment of the present invention is provided. Figure 1 , and is generally indicated by reference numeral 100. Figure 1As shown, the protection circuit 100 includes an input terminal 102, an output terminal 104, two switch devices 106, 108, and a control circuit 110 that communicates with the two switch devices 106, 108, wherein the input terminal 102 is used to connect to a power supply (not shown) to receive an input voltage Vin, and the output terminal 104 is used to connect to a power converter (not shown) to provide an output voltage Vout to the power converter. The switch device 106 is connected in a current path between the input terminal 102 and the output terminal 104, and can be controlled to be turned on during the startup of the power converter. The switch device 108 is connected across the switch device 106. The control circuit 110 is configured to sense the input voltage Vin and the output voltage Vout, disconnect the switch device 106 and turn on the switch device 108 to supply power to the power converter in response to the output voltage Vout exceeding a defined output voltage threshold, and disconnect the switch device 108 to cut off the connection between the power supply and the power converter in response to the input voltage Vin exceeding a defined input voltage threshold.

[0051] Therefore, by using the protection circuit 100 and / or any other protection circuit disclosed herein to disconnect the power supply from the power converter, overvoltage protection is provided for the power converter to prevent excessive input voltage. This is particularly useful in applications (e.g., outdoor applications, etc.) that require excessive overvoltage protection (such as at least 150% of the rated input voltage).

[0052] As described above, during the startup of the power converter, the switching device 106 is turned on (e.g., in a closed position). During this period of time, the switching device 108 is initially turned off (e.g., in an open position). Therefore, current from the input power supply can flow to the power converter via the switching device 106 to, for example, charge the effective capacitance of the power converter. After the effective capacitance is sufficiently charged, the control circuit 110 turns off the switching device 106 and turns on the switching device 108.

[0053] When the output voltage Vout reaches the defined output voltage threshold, the capacitor of the power converter can be fully charged. Figure 1 As shown, the protection circuit includes an output sensor 114 (such as a resistive voltage sensor, etc.) connected across the output terminal 104. The control circuit 110 receives a signal representing the output voltage Vout from the output sensor 114. In response to the control circuit 110 determining that the output voltage Vout has reached the defined output voltage threshold, the control circuit 110 may send a control signal to the switch device 106 to open the switch device 106, and send a control signal to the switch device 108 to close the switch device 108. At this time, power is supplied from the power supply to the power converter via the closed switch device 108.

[0054] In this example, the defined output voltage threshold may be equal to the rated peak voltage of the input voltage Vin. Therefore, if the input voltage Vin is an AC input voltage, the defined output voltage threshold may be equal to the rated peak voltage of the AC input voltage. In this example, the defined output voltage threshold may be 85V, 120V, 220V, 250V, 275V, 300V, etc.

[0055] If the input voltage Vin exceeds the defined input voltage threshold, the switch device 108 is turned off. Figure 1 As shown, the protection circuit includes an input sensor 112 (such as a resistive voltage sensor, etc.) connected across the input terminal 102. In this example, the control circuit 110 receives a signal representing the input voltage Vin from the sensor 112. In response to the control circuit 110 determining that the input voltage Vin has reached a defined input voltage threshold, the control circuit 110 may send a control signal to the switch device 108 to disconnect the switch device 108. At this time, the switch device 108 and the switch device 106 are both disconnected, thereby cutting off the connection between the power converter and the power supply providing the excessive input voltage.

[0056] The defined input voltage threshold may be any suitable value higher than the rated peak voltage of the input voltage Vin. For example, the defined input voltage threshold may be a set value higher than the rated peak voltage of the power supply. For example, if the input voltage Vin is an AC input voltage, the defined input voltage threshold may be equal to a voltage that is at least 120% of the rated peak voltage of the AC input voltage. In such an example, if the rated peak voltage of the AC input voltage is 275V, the input voltage threshold may be set to 330V (e.g., 275V×1.2). In other examples, the defined input voltage threshold may be equal to a voltage that is at least 150%, at least 173%, etc., of the rated peak voltage of the AC input voltage.

[0057] In other examples, the switching device 108 can be turned off when the input voltage Vin exceeds a defined input voltage threshold for a defined time period. This may be useful when the power converter can withstand instantaneous spikes in the input voltage. In such an example, the defined time period may be based on a defined input voltage threshold. For example, if the input voltage threshold is set to a higher value (e.g., 173% of the rated peak voltage of the input voltage), the defined time period may be set to a shorter time period (e.g., 200 milliseconds, etc.). Conversely, if the input voltage threshold is set to a lower value (e.g., 150% of the rated peak voltage of the input voltage), the defined time period may be set to a longer time period (e.g., 5 seconds, etc.).

[0058] In addition, the switching device 108 may be opened based on the bulk output voltage across the capacitor. For example, if the rated peak voltage of the AC input voltage is 275 V, the bulk output voltage across the capacitor may reach 396 V during normal operation. In such an example, the switching device 108 may be opened if the bulk output voltage exceeds 560 V for 1 millisecond, exceeds 540 V for 50 milliseconds, exceeds 500 V for 5 seconds, etc.

[0059] In some examples, the control circuit 110 can control the switching device 106 to turn on during startup of the power converter. For example, and as described above, when the power converter is enabled (e.g., during startup of the power converter, etc.), the control circuit 110 can send a control signal to the switching device 106 to close the switching device. In other examples, and as further explained below, the switching device 106 can be turned on based on an auxiliary supply source, an input voltage, etc.

[0060] For example, Figure 2 A power supply device 200 including a protection circuit 202 having a self-biased switching device is shown. Specifically, the power supply device 200 includes a protection circuit 202 having a self-biased MOSFET Q1 and a relay K1, a power circuit 218 receiving power from an AC power source 216 via the protection circuit 202, an input voltage sensor 212, an output voltage sensor 214, and a control circuit 210. As shown in the figure, the power converter 218 includes an AC / DC power factor correction (Power Factor Correction, PFC) circuit 220 and a DC / DC power conversion circuit 222 connected between the PFC circuit 220 and the load.

[0061] The MOSFET Q1 and relay K1 of the protection circuit 202 may be similar to Figure 1 The switch device 106 and the switch device 108 are shown in FIG. Figure 2 As shown, MOSFET Q1 is coupled in a current path between an input of protection circuit 202 (eg, power source 216 ) and an output of protection circuit 202 (eg, power converter 218 ), and relay K1 is coupled across MOSFET Q1 .

[0062] As described above, the MOSFET Q1 of the protection circuit 202 is self-biased. For example, Figure 2 MOSFET Q1 can be self-biased in response to an input voltage from power supply 216. Specifically, and as Figure 2As shown, the protection circuit 202 includes a resistor R1 connected between the drain terminal and the gate terminal of the MOSFET Q1, and a resistor R2 connected between the gate terminal and the source terminal of the MOSFET Q1. The resistor R1 and the resistor R2 form a voltage divider circuit. Therefore, when the power supply 216 provides its input voltage to the protection circuit 202, a sufficient voltage is applied to the gate terminal of the MOSFET Q1 via the voltage divider circuit to bias the MOSFET Q1, thereby turning on the MOSFET Q1.

[0063] exist Figure 2 In a specific example of the present invention, resistor R1 may have a larger resistance value, and resistor R2 may have a smaller resistance value than R1. For example, the value of resistor R1 may be approximately 100 kilo-ohms, and the value of resistor R2 may be approximately 15 kilo-ohms. In other examples, resistors R1 and R2 may have other suitable resistance values ​​(such as greater than or less than 100 kilo-ohms, greater than or less than 15 kilo-ohms, etc.).

[0064] like Figure 2 As shown, the control circuit 210 includes a controller 224 and a photocoupler U1. The controller 224 may include various components for controlling the MOSFET Q1 and the relay K1 based on the input voltage sensed from the voltage sensor 212 and the output voltage sensed from the voltage sensor 214. Figure 3 Shows Figure 2 An example of a controller 224.

[0065] For example, and if Figure 3 As shown, the controller 224 includes a microcontroller (MCU) 326 and a driver 328, a driver 330. The MCU 326 includes a comparator 332, a comparator 334, and a logic component 336. During operation, the controller 224 receives a sensed input voltage from the voltage sensor 212 and a sensed output voltage from the voltage sensor 214. In some examples, the MCU 326 and / or the sensor 212, the sensor 214 may include one or more analog-to-digital converters (not shown) to convert the sensed input voltage and / or the sensed output voltage into a digital signal. The comparator 332 compares the sensed input voltage with a defined threshold value Vth1, and the comparator 334 compares the sensed output voltage with a defined threshold value Vth2. The logic component 336 receives the comparison results from the comparators 332, the comparator 334, and generates a signal for the driver 328, the driver 330 to drive the MOSFET Q1 (via the optocoupler U1) and the relay K1. Figure 3 The values ​​of the defined thresholds Vth1 and Vth2 can be similar to Figure 1 The value that defines the threshold.

[0066] In other examples, the control circuit 210 may include other suitable components for controlling the MOSFET Q1 and the relay K1. For example, the optocoupler U1 may be replaced with a magnetically coupled switching device such as a relay.

[0067] exist Figure 2 and Figure 3 In the example of , the control circuit 210 is powered by a supply voltage. The supply voltage can be provided by an input power supply and / or by an auxiliary supply source. In this example, if necessary, the supply voltage can also provide power for driving the relay K1.

[0068] The control circuit 210 can be used with Figure 1 The control circuit 110 functions in a similar manner. For example, Figure 4 A timing diagram 400 is shown, which includes a timing diagram 400 from Figure 2 4 shows waveforms of different parameters of the power supply device 200. Specifically, waveform 402 represents the rectified input voltage Vr provided to the protection circuit 202, waveform 404 represents the output voltage Vo of the protection circuit 202, waveform 406 represents the bulk voltage Vb between the PFC circuit 220 and the DC / DC power conversion circuit 222, waveform 408 represents the state of the relay K1, waveform 410 represents the state of the MOSFET Q1, waveform 412 represents the signal PFC for turning on / off the PFC circuit, and waveform 414 represents the signal CONV for turning on / off the DC / DC power conversion circuit.

[0069] At startup, the input voltage Vr is at the rated peak voltage, as shown in waveform 402, and since the input voltage provides a bias voltage to the gate terminal of the MOSFET, the MOSFET Q1 is closed (as described above), the relay K1 is opened, and the optocoupler U1 of the control circuit 210 is deactivated (e.g., opened). Figure 4 As shown, the signal PFC and the signal CONV are high, indicating that the PFC circuit and the DC / DC power conversion circuit are disconnected. In this example, current flows through the protection circuit 202 via the MOSFET Q1, thereby increasing the output voltage Vo as the capacitor C (e.g., representing the effective capacitance of the power converter 218) is charged. During this period, the MOSFET Q1 can be operated in the PWM mode at a switching frequency of 100 Hz-120 Hz. In some examples, the MOSFET Q1 can be operated in its active mode to charge the capacitor C.

[0070] After time period t1, the sensed voltage (proportional to the output voltage Vo) reaches a defined threshold value Vth2. In response, the control circuit 210 generates a control signal to turn on (e.g., close) the relay K1, as shown by the waveform 408 transitioning to a high state. This provides a minimum series impedance path for the current flowing through the protection circuit 202 to the power converter 218. In some examples, the time period t1 may be approximately 6 seconds.

[0071] After the relay K1 is closed, the control circuit 210 activates the optocoupler U1 to disconnect (e.g., turn off) the MOSFET Q1, as shown by the waveform 410 transitioning to a low state. For example, when the optocoupler U1 is turned on, current is drawn from the gate terminal of the MOSFET Q1, causing the MOSFET Q1 to turn off. During this period, when the MOSFET Q1 is turned off, the resistor R1, the resistor R2 sets the minimum charging current.

[0072] like Figure 4 As shown, a delay (eg, time period t2) may occur between closing relay K1 and opening MOSFET Q1. In some examples, the delay may be approximately 50 milliseconds.

[0073] After MOSFET Q1 is turned off, control circuit 210 may control relay K1 in PWM mode, as shown by waveform 408 which repeatedly switches between a high state and a low state. This ensures that the output voltage Vo is maintained at a constant level. Figure 4 As shown, a delay (eg, time period t3) may occur between turning off MOSFET Q1 and entering PWM mode. The delay may be approximately 450 milliseconds.

[0074] When relay K1 is operating in its PWM mode, signal PFC transitions to a low state to turn on the PFC circuit. This may occur at time period t4 (e.g., 500 milliseconds) after relay K1 is operating in its PWM mode. Once the PFC circuit is started, the PFC output voltage Vb is regulated, for example, to a level higher than the peak AC input. This is shown at the end of time period t4 in waveform 406.

[0075] After starting the PFC circuit, the signal CONV transitions to a low state to turn on the DC / DC power conversion circuit. In some examples, a delay (e.g., time period t5) may occur between starting the PFC circuit and starting the DC / DC power conversion circuit. This ensures that the output of the PFC circuit is sufficient for the DC / DC power conversion circuit. In some examples, the delay may be about 2 seconds. At this point, the power converter 218 may be in a stable state to provide an output voltage (e.g., a regulated output voltage) to the load.

[0076] At some point, during time period t8, the input voltage Vr may increase, resulting in Figure 4 The overvoltage state OV PLD shown in FIG. 4 may cause the output voltage Vo and the PFC output voltage Vb to reach a peak, as shown in waveforms 404 and 406, and cause the signal PFC to transition to a high state to disable the PFC circuit. Subsequently, the signal CONV transitions to a high state (e.g., after the output of the PFC circuit decays) to disable the DC / DC power conversion circuit. This initiates an overvoltage recovery condition, as shown in time period t9.

[0077] At the beginning of time period t8, control circuit 210 determines that the sensed input voltage has exceeded the defined threshold value Vth1. In response, control circuit 210 disconnects (e.g., turns off) relay K1, as shown in waveform 408 that switches to a low state. At this time, resistor R1, resistor R2 provide the only current path between power supply 216 and power converter 218. However, as described above, since resistor R1 has a high resistance, the amount of current passing through this path is negligible. Therefore, after disconnecting relay K1, the connection between power converter 218 and power supply 216 is effectively cut off. After cutting off power converter 218, capacitor C discharges, causing output voltage Vo (waveform 404) and PFC output voltage Vb (waveform 406) to decrease.

[0078] Once the input voltage Vr decreases, the power supply device 200 may enter the on-delay period TON DELAY. Figure 4 As shown. During this period, the power converter 218 is reconnected to the power source 216 via the MOSFET Q1. For example, in response to the input voltage dropping below the defined threshold value Vth1, the control circuit 210 can disconnect the optocoupler U1. Therefore, as described above, the MOSFET Q1 is turned back on due to the bias voltage from the input voltage, thereby charging (or recharging) the capacitor C. After this, the aforementioned steps can be repeated to return the power converter 218 to its stable state as described above.

[0079] In some examples, the protection circuits disclosed herein may include a current limiting function. In such examples, the protection circuit may include a circuit for limiting the inrush current from the input power supply. For example, Figure 5 A power supply 500 is shown that is substantially similar to power supply 200 , but includes an inrush current limiting circuit 540 . Figure 5 The power supply device 500 includes a protection circuit 502 having an inrush current limiting circuit 540 coupled to the MOSFET Q1. Specifically, and as Figure 5As shown, the inrush current limiting circuit 540 is coupled between the MOSFET Q1 and the power converter 218. Thus, when the input voltage is present, the inrush current limiting circuit 540 can limit the input current to ensure that a controlled amount of current flows through the MOSFET Q1 to the power converter 218.

[0080] like Figure 5 As shown, the inrush current limiting circuit 540 includes a resistor R3 and a transistor Q2. The resistor R3 is connected between the MOSFET Q1 and the transistor Q2. Specifically, one end of the resistor R3 is connected to the source terminal of the MOSFET Q1 and the base terminal of the transistor Q2 (via the resistor R4), and the other end of the resistor R3 is connected to the emitter terminal of the transistor Q2. The collector terminal of the transistor Q2 is connected to the gate terminal of the MOSFET Q1.

[0081] When operating, the inrush current limiting circuit 540 controls the amount of current flowing through the protection circuit 502. For example, if the input current increases, the voltage drop across the resistor R3 increases. Once the voltage drop across the resistor R3 reaches the base-emitter voltage Vbe of the transistor Q2, the transistor Q2 is turned on (and operates in its active mode). Therefore, some of the current applied to the gate terminal of the MOSFET Q1 flows through the transistor Q2. This causes the gate-source voltage Vgs of the MOSFET Q1 to decrease, thereby reducing the conductivity of the MOSFET Q1 and limiting the current flowing through the MOSFET Q1. Therefore, the input current flowing through the MOSFET Q1 (and provided to the power converter 218) can be limited to a fixed value determined by the resistor R3 and the transistor Q2.

[0082] Resistor R3 can be any suitable value for producing a voltage drop to limit the current flowing through MOSFET Q1. In some examples, the value of resistor R3 can be very low (such as less than about 5 ohms). In other examples, the value can be higher if necessary.

[0083] like Figure 5 As shown, the protection circuit 502 also includes a resistor R4 coupled to the transistor Q2. Specifically, one end of the resistor R4 is coupled to the base terminal of the transistor Q2, and the other end of the resistor R4 is coupled to the resistor R3 and the source terminal of the MOSFET Q1. During operation, the resistor R4 limits the base voltage on the transistor Q2 so that the base voltage does not exceed the rated value of the set base-emitter voltage Vbe.

[0084] In other examples, the protection circuit may have another suitable inrush current limiting circuit. Figure 6 A power supply 600 is shown that is substantially similar to power supply 500, but includes a different inrush current limiting circuit. Figure 6 In the example of FIG. 6 , the power supply 600 includes a protection circuit 602 having an inrush current limiting circuit 640 coupled to the MOSFET Q1. Specifically, the inrush current limiting circuit 640 includes a resistor R5 coupled between the MOSFET Q1 and the power converter 218 for limiting the input current to ensure that a controlled amount of current flows through the MOSFET Q1.

[0085] exist Figure 6 In the specific example of , MOSFET Q1 can be operated in a switching mode. Therefore, if the input current increases, the voltage drop across resistor R5 increases. As described above, this voltage drop can reduce the gate-source voltage Vgs of MOSFET Q1, thereby limiting the current flowing through MOSFET Q1.

[0086] Figure 7 7 is a power supply device 700 that is substantially similar to the power supply device 600, but in the power supply device 700, the MOSFET Q1 is controlled to be turned on based on the auxiliary supply source. Figure 7 As shown, the power supply device 700 includes a protection circuit 702 having an auxiliary supply source AS, which is coupled to the gate terminal of the MOSFET Q1 for providing a bias voltage to the MOSFET Q1. More specifically, the auxiliary supply source AS is coupled between the resistor R1 and the photocoupler U1.

[0087] During operation, MOSFET Q1 can be turned on based on the bias voltage applied by the auxiliary supply source AS. For example, upon sensing the input voltage, the control circuit 210 can activate the optocoupler U1. Therefore, the auxiliary supply source AS provides the bias voltage to the gate terminal of the MOSFET Q1 via the voltage divider (formed by resistor R1, resistor R2) as described above.

[0088] like Figure 1 , Figure 2 as well as Figure 5-Figure 7 As shown in the example of, the protection circuit 100, the protection circuit 202, the protection circuit 502, the protection circuit 602, and the protection circuit 702 are connected to the high side rail (e.g., positive rail, power rail, etc.) between the power supply and the power converter. In other examples, any protection circuit disclosed herein can be connected to the low side rail (e.g., reference rail, return rail, etc.). For example, Figure 8 A power supply 800 is shown that is substantially similar to power supply 700 , but has a protection circuit 802 coupled in the low-side rail between power source 216 and power converter 218 .

[0089] In some examples, the protection circuits disclosed herein may include additional optional circuits. Figure 5-Figure 8As shown, the protection circuit 502, the protection circuit 602, the protection circuit 702, and the protection circuit 802 all include a voltage regulating circuit to protect the MOSFET Q1. Specifically, and as Figure 5-Figure 8 As shown, the protection circuit 502, the protection circuit 602, the protection circuit 702, and the protection circuit 802 all include a diode (e.g., a Zener diode) D5 and a capacitor C2 connected in parallel with the diode D5. The diode D5 and the capacitor C2 are connected between the gate terminal and the source terminal of the MOSFET Q1. In operation, the combination of the diode D5 and the capacitor C2 limits (e.g., clamps) the gate-source voltage Vgs of the MOSFET Q1.

[0090] In addition, the power supply device disclosed herein may include additional optional circuits. For example, Figure 2 and Figure 5-Figure 8 As shown, the power supply device 200, the power supply device 500, the power supply device 600, the power supply device 700, and the power supply device 800 all include an electromagnetic interference (EMI) filter and a rectifier circuit connected between the AC power source 216 and the protection circuit 202, the protection circuit 502, the protection circuit 602, the protection circuit 702, and the protection circuit 802. Figure 2 and Figure 5-Figure 8 In the specific example of FIG. 1 , the rectifier circuit is shown as a diode bridge. In other examples, another suitable rectifier circuit may be used if necessary. In addition, although the power supply device 200, the power supply device 500, the power supply device 600, the power supply device 700, and the power supply device 800 include an EMI filter and a rectifier circuit, it is obvious to those skilled in the art that any component of the EMI filter and the rectifier circuit may be removed and moved to another suitable location (such as on the output side of the protection circuit, etc.).

[0091] The sensor disclosed herein can be any suitable sensing device. For example, the sensor can be a sensor using Figure 2 and Figure 5-Figure 8 The resistive voltage sensor formed by the voltage divider shown. In other examples, another suitable voltage sensing device can be used. Additionally and / or alternatively, the sensor can sense a parameter other than the input voltage and / or the output voltage. In such an example, the parameter can be used to determine (e.g., calculate, estimate, etc.) the input voltage and / or the output voltage.

[0092] In addition, if Figure 2 and Figure 5-Figure 8 As shown, the input voltage sensor is connected to sense the AC input voltage. In other examples, Figure 2 and Figure 5-Figure 8The input voltage sensor can be connected at another suitable location to sense the input voltage. For example, if necessary, the input voltage sensor can be connected to the output side of the rectifier circuit to sense the rectified AC input voltage.

[0093] The switching devices disclosed herein may include any suitable active switching devices. Figure 2 and Figure 5-Figure 8 In a specific example of, the protection circuit includes a MOSFET Q1 connected in a current path between its input and output terminals and a relay K1 connected across the MOSFET Q1. In this example, the MOSFET Q1 may be an N-channel FET and the relay K1 may be a normally open relay. In other examples, if necessary, the MOSFET Q1 may be replaced with another suitable transistor (such as an insulated-gate bipolar transistor (IGBT)), and / or the relay K1 may be replaced with another suitable switching device. In some examples, the switching device may be selected based on the Safe Operating Area (SOA) performance to ensure that the switching device may be safely operated.

[0094] The power supply disclosed herein may include any suitable power supply. For example, the power supply may include Figure 2 and Figure 5-Figure 8 The AC power source shown. In such an example, the AC power source may include a power grid, a generator, etc. In other examples, the power source may include a DC power source (such as one or more batteries (e.g., rechargeable batteries), etc.).

[0095] The power converter disclosed herein may include any suitable power conversion circuit. For example, Figure 2 and Figure 5-Figure 8 As shown, the power converter may include an AC / DC power converter (such as an AC / DC PFC circuit) and a DC / DC power conversion circuit. In other examples, the power converter may include a DC / DC power converter. For example, Fig. 9 A power supply 900 is shown that is substantially similar to power supply 200, but has a protection circuit 902 coupled between a DC power source 916 and a DC / DC power converter 918. In this example, the protection circuit 902 includes a diode D coupled between the MOSFET Q1 and the DC power source 916 to provide reverse current protection. As shown, the DC / DC power converter 918 may include a boost converter and a DC / DC power conversion circuit.

[0096] Fig. 9The protection circuit 902 may include any one or more of the optional features described herein. For example, although not shown, the protection circuit 902 may include a circuit for limiting inrush current (such as Figure 5 and Figure 6 ) In addition, MOSFET Q1 can respond to power from power source 916 (such as Fig. 9 ) and / or based on an input voltage such as Figure 7 In addition, the protection circuit 902 can be connected in the high side rail (such as Fig. 9 ), or in a low side rail as described herein.

[0097] In addition, the power converter may include any suitable power conversion topology having one or more power switching devices. For example, the power converter may include one or more of a buck topology, a boost topology, a buck-boost topology, a forward topology, a flyback topology, a half-bridge topology, a full-bridge topology, and / or resonant counterparts thereof.

[0098] The control circuit disclosed herein may include an analog control circuit, a digital control circuit, or a hybrid control circuit (e.g., a digital control unit and an analog circuit). The digital control circuit may be implemented using one or more types of digital control circuits. For example, the digital control circuit may include a digital signal controller (DSC), a digital signal processor (DSP), an MCU, a field programmable gate array (FPGA), an application-specific integrated circuit (ASIC), etc. In some examples, the control circuit may be used to control the switching device of the protection circuit and at least a portion of the power converter connected to the protection circuit. For example, in Figure 4 In a specific example of FIG. 2 , the control circuit 210 includes an MCU 326 for controlling the MOSFET Q1 and the relay K1. In some examples, the MCU 326 can also control the PFC circuit portion if necessary.

[0099] If, for example, the control circuit is a digital control circuit, the control circuit may be implemented using one or more hardware components and / or software. For example, instructions for performing any one or more features disclosed herein may be stored in a non-transitory computer-readable medium, etc. and / or transferred from a non-transitory computer-readable medium, etc. to one or more existing digital control circuits, new digital control circuits, etc. In such examples, one or more instructions may be stored in a volatile memory, a non-volatile memory, a ROM, a RAM, one or more hard disks, a disk drive, an optical drive, a removable memory, a non-removable memory, a tape cartridge, a flash memory card, a CD-ROM, a DVD, a cloud storage, etc.

[0100] The power supply disclosed herein can be used in any of a variety of applications. For example, the power supply can be used in outdoor power supply applications that require excessive overvoltage protection (such as at least 150% of the rated input voltage), high-efficiency power supply applications, power supply applications including high-density conduction cooling systems, etc. In some examples, the power supply can receive an AC input voltage between 85VAC and 275VAC.

[0101] The protection circuit disclosed herein provides a compact and effective method with precise timing control to protect components (e.g., MOSFETs, diodes, capacitors, etc.) in a power converter. For example, and as described herein, the protection circuit can provide protection during an input overvoltage condition by disconnecting the power converter from the input power supply, during an excessive input current condition by precisely controlling the input inrush current to limit the amount of current flowing to the power converter, and so on. In addition, the protection circuit can provide overvoltage and / or inrush current protection with significantly reduced losses and improved efficiency compared to conventional methods. In addition, the protection circuit can be relatively easy to implement in high-density power supply applications, requires less circuit board space, and requires less complexity in thermal management solutions compared to conventional methods including multiple relays.

[0102] For the purpose of illustration and description, the foregoing description of the embodiment has been provided. This is not intended to be exhaustive or limit the present invention. Each element or feature of a particular embodiment is generally not limited to the particular embodiment, but when applicable, can be interchangeable and can be used in a selected embodiment, even if not specifically shown or described. Each element or feature of a particular embodiment can also be changed in a variety of ways. These changes should not be considered as departing from the present invention, and all these modifications are intended to be included within the scope of the present invention.

Claims

1. A power supply device, comprising: Power converter; a protection circuit comprising an input terminal coupled to a power source for receiving an input voltage, an output terminal coupled to the power converter for providing an output voltage to the power converter, a first transistor coupled in a current path between the input terminal and the output terminal, a relay coupled across the first transistor, and a second transistor coupled to the first transistor and configured to limit a current flowing through the first transistor, the first transistor being controllable to be turned on during startup of the power converter; as well as a control circuit in communication with the first transistor and the relay, the control circuit being configured to sense the input voltage and the output voltage, control the first transistor to be turned off and the relay to be turned on to supply power to the power converter in response to the output voltage exceeding a first defined threshold, and control the relay to be turned off to cut off the connection between the power source and the power converter in response to the input voltage exceeding a second defined threshold, Wherein, the input voltage is an AC input voltage; wherein the first defined threshold is the rated peak voltage of the AC input voltage, and Wherein, the second defined threshold is a voltage of at least 120% of the rated peak voltage of the AC input voltage.

2. The power supply device according to claim 1, wherein: The first transistor is a self-biased MOSFET configured to turn on in response to the input voltage.

3. The power supply device according to claim 1, wherein: The control circuit is configured to open the relay to disconnect the power source from the power converter in response to the input voltage exceeding the second defined threshold for a defined period of time.

4. The power supply device according to claim 3, wherein: The defined time period is based on the second defined threshold.

5. The power supply device according to claim 1, wherein: The control circuit is configured to control the first transistor to turn on during startup of the power converter.

6. A power supply device, comprising: Power converter; a protection circuit, the protection circuit comprising an input terminal coupled to a power source for receiving an input voltage, an output terminal coupled to the power converter for providing an output voltage to the power converter, a first switching device coupled in a current path between the input terminal and the output terminal, and a second switching device coupled across the first switching device, the first switching device being controllable to be turned on during startup of the power converter; as well as a control circuit in communication with the first switching device and the second switching device, the control circuit being configured to sense the input voltage and the output voltage, to turn off the first switching device and turn on the second switching device to supply power to the power converter in response to the output voltage exceeding a first defined threshold, and to turn off the second switching device to disconnect the power source from the power converter in response to the input voltage exceeding a second defined threshold, Wherein, the input voltage is an AC input voltage; wherein the first defined threshold is the rated peak voltage of the AC input voltage, and Wherein, the second defined threshold is a voltage of at least 120% of the rated peak voltage of the AC input voltage.

7. The power supply device according to claim 6, wherein: The first switching device is a self-biased switching device configured to turn on in response to the input voltage.

8. The power supply device according to claim 6, wherein: The control circuit is configured to turn on the first switching device during startup of the power converter.

9. The power supply device according to claim 6, wherein: The first switching device is a MOSFET, and the second switching device is a relay.

10. The power supply device according to claim 6, wherein: The control circuit is configured to open the second switching device to disconnect the power source from the power converter in response to the input voltage exceeding the second defined threshold for a defined period of time. 11 . The power supply device of claim 6 , further comprising at least one of a resistor and a third switching device coupled to the first switching device to limit a current flowing through the first switching device.

12. The power supply device according to claim 6, wherein: The power converter includes a PFC circuit.

13. A protection circuit, the protection circuit being used to be connected between a power supply and a power converter to provide input overvoltage protection for the power converter, the protection circuit comprising an input terminal configured to be connected to the power supply for receiving an input voltage, an output terminal configured to be connected to the power converter for providing an output voltage to the power converter, a first switching device connected in a current path between the input terminal and the output terminal, a second switching device connected across the first switching device, and a control circuit communicating with the first switching device and the second switching device, wherein the first switching device can be controlled to be turned on during startup of the power converter, the control circuit being configured to sense the input voltage and the output voltage, disconnect the first switching device and turn on the second switching device to supply power to the power converter in response to the output voltage exceeding a first defined threshold, and disconnect the second switching device to cut off the connection between the power supply and the power converter in response to the input voltage exceeding a second defined threshold, in, The input voltage is an AC input voltage; wherein the first defined threshold is the rated peak voltage of the AC input voltage, and Wherein, the second defined threshold is a voltage of at least 120% of the rated peak voltage of the AC input voltage.

14. The protection circuit according to claim 13, wherein: The first switching device is a self-biased switching device configured to turn on in response to the input voltage.

15. The protection circuit according to claim 14, wherein: The first switching device is a MOSFET, and the second switching device is a relay.

16. The protection circuit according to claim 13, wherein: The control circuit is configured to open the second switching device to disconnect the power source from the power converter in response to the input voltage exceeding the second defined threshold for a defined period of time. 17 . The protection circuit of claim 13 , further comprising at least one of a resistor and a third switching device coupled to the first switching device to limit a current flowing through the first switching device.

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