Electronic protection system and control

Abstract

The present disclosure relates to electronic protection systems and controls. A protection IC protects an external load connected to a mains supply line from dangerous or undesirable conditions such as overvoltage, undervoltage, and overcurrent by disconnecting the external load for at least the duration of such conditions. The IC has a range detector, a zero-crossing detector, a control unit, a switch driver, and a dummy DAC. The range detector senses the presence of an unwanted condition. The control unit then waits for a zero-crossing, at which time the load is disconnected. A lock timer can introduce a minimum wait time before reconnecting the load. To prevent instability around the switching point, hysteresis in the window threshold prevents the effects of noise. The dummy DAC regulates a dummy current, which linearizes the IC current consumption around the switching point to prevent instability caused by positive feedback in the non-linear transition.

Description

[0001] Cross-references to related applications

[0002] This application claims priority to U.S. Provisional Patent Application No. 63,167,653, filed March 30, 2021, entitled Electronic Fuse System and Method, which is incorporated herein by reference for all purposes as if fully set forth in this application.

[0003] This application claims priority to U.S. Provisional Patent Application No. 63,231,886, filed August 11, 2021, entitled High-Reliability Low-Loss PowerSwitch and Driver IC, which is incorporated herein by reference for all purposes as if fully set forth herein. Technical Field

[0004] The disclosed embodiments generally relate to systems and methods used in power management, and more specifically to those used in overvoltage protection systems and electronic protection systems. The embodiments may be implemented as integrated circuits or otherwise. The embodiments can be used to protect against overvoltage and undervoltage events, but can also be used for sensing and precise monitoring. Background Technology

[0005] Unpredictable fluctuations in the power supplied by alternating current (AC) trunk lines can damage electronic and electrical equipment, leading to economic losses or worse. They can also cause interference, resulting in incorrect or unsafe operation of sensitive equipment.

[0006] One effect of overvoltage is that electronic devices heat up and suffer thermal damage. For example, an electrolytic capacitor might only heat up slightly from a very short voltage spike, but if this continues, the capacitor will burn out. This can cause a short circuit or open circuit, leading to the cessation of electronic system operation. Semiconductors will be damaged by overvoltage even faster. Undervoltage also causes problems, particularly regarding the reliability of system operation.

[0007] Conventionally, power supply fluctuations are addressed using discrete solutions that include resistors and capacitors. While such solutions are often inexpensive, they have a limited lifespan because they can only handle a fixed number of voltage spikes. Therefore, they can provide false protection when one of the protective devices fails.

[0008] Another problem is that electronic protection systems become unstable near overvoltage and undervoltage thresholds due to naturally occurring noise. To address this, these thresholds are designed with hysteresis. However, electronic protection systems powered from a high-voltage source via resistors may still suffer from instability around the switching point. This instability cannot be solved simply by applying hysteresis.

[0009] Some conventional electronic protection systems switch quickly, but they suffer from large voltage spikes when power is interrupted.

[0010] Clearly, there is an unmet need for solid-state solutions with low cost and small footprint (i.e., implemented as integrated circuits). However, these solutions also need to be able to handle voltage spikes indefinitely and autonomously, very quickly, without causing spikes and other undesirable behaviors, and without instability.

[0011] Unless otherwise stated herein, the elements described in this section are not prior art to the claims and are not acknowledged as prior art by virtue of their inclusion in this section. Summary of the Invention

[0012] The disclosed technology recognizes that in electronic protection circuits, not all instabilities are caused by natural noise occurring on the mains voltage; some may be due to positive feedback problems caused by operational nonlinearity. Electronic protection systems protect external loads from overvoltage, undervoltage, and / or overcurrent conditions on the mains supply line by disconnecting the load from the mains supply line in the event of a hazardous situation. The requirement for efficient execution leaves a small energy budget for electronic protection systems. The energy flowing into and out of the sensing and switching driver terminals of an integrated circuit (IC) can be significant relative to the power used internally. Activating a fuse requires additional power, both for internal operation and for devices connected to its pins, thus altering the IC's internal supply level and affecting the reference voltage used for the threshold. The effect can be negative, creating an inherently stable feedback loop, or positive, creating an inherently unstable feedback loop. Implementations use one or more variable dummy currents and / or external filters associated with the current flowing into and out of the pins to reduce or reverse supply current discontinuities across the threshold. Dummy currents can be generated using a DAC, a dummy resistor, or a dummy current source. A DAC with a current source output can be controlled by the supply voltage level. Lowering or reversing the power swing reduces or eliminates positive feedback during threshold crossings, thus stabilizing the implementation.

[0013] In a first aspect, one embodiment provides an electronic protection circuit. The circuit may be an IC. The circuit has a power supply terminal, a common terminal, a sensing terminal, one or more zero-crossing detection input terminals, and a switch driver output terminal. Coupled between the power supply terminal and the common terminal is a dummy DAC, which may be controlled by a control unit. A zero-crossing detector is coupled between one or more zero-crossing detection input terminals and the control unit. The zero-crossing detector is operable to determine the time of zero crossing in a signal applied to the one or more zero-crossing detection input terminals and signal those times to the control unit. A range detector is coupled between the sensing terminal and the control unit. It is operable to determine whether a peak value of an external unprocessed supply voltage is within or outside an allowable range. The allowable range may be widened or narrowed. The range detector delivers a range detection output signal that signals the range condition and the out-of-range condition associated with whether the peak value of the external unprocessed supply voltage is within or outside the allowable range. Between the range detector and the control unit may be a lockout timer with a configurable lockout duration. The lockout timer ensures that the control unit does not receive a range signal from the range detector unless at least the lockout duration has elapsed since the start or end of an out-of-range signal. This allows for some thermal recovery time after the electronic protection circuit disconnects the external load from the mains power supply line upon detecting a dangerous condition. The dummy DAC has a current output. It supplies dummy current to prevent instability caused by positive feedback during changes in IC operation, wherein the dummy current flows from the power supply terminal through the dummy DAC to the common terminal.

[0014] In a second aspect, one embodiment provides a method for protecting a load from overvoltage or undervoltage conditions in an untreated supply voltage. The method first decouples the load from the untreated supply voltage and initializes the dummy current to a first value in a protection IC. The IC then senses the untreated supply voltage and determines whether its peak value is within a narrowed allowable range. If so, it widens the allowable range to become the widened allowable range. It waits for a first zero crossing, which could be a zero crossing of the untreated supply voltage or a zero crossing of a voltage measured at a switch. It then changes the dummy current to a second value and couples the load to the untreated supply voltage. The method continues to determine whether the untreated supply peak value is outside the widened allowable range. If so, it narrows the allowable range again, then waits for a second zero crossing, changes the dummy current to a third value, and decouples the load from the untreated supply voltage.

[0015] A further understanding of the nature and advantages of the particular embodiments disclosed herein can be achieved by referring to the remainder of the specification and the accompanying drawings. Attached Figure Description

[0016] The disclosed technology will be described with reference to the accompanying drawings, in which:

[0017] Figure 1 A low-cost electronic protection system in an embodiment of the disclosed technology is shown;

[0018] Figure 2A -D shows a summary curve of the supply current drawn by the electronic protection system as a function of the mains voltage.

[0019] Figure 3 The illustration shows a first example electronic protection circuit in an embodiment of the disclosed technology;

[0020] Figure 4 The illustration shows a second example electronic protection circuit in an embodiment of the disclosed technology;

[0021] Figure 5 The illustration shows an example electronic protection system in an embodiment of the disclosed technology, including, for example... Figure 3 As shown or as Figure 4 The electronic protection circuit shown;

[0022] Figure 6 The illustration shows details of a filter that provides power stability in an embodiment of the disclosed technology; and

[0023] Figure 7 The illustration shows a method for preventing overvoltage and undervoltage conditions in an embodiment of the disclosed technology.

[0024] In the figures, similar reference numerals may indicate elements with similar functions. The systems and methods shown in the figures and described in the detailed embodiments below can be arranged and designed in a variety of different ways. The figures and detailed embodiments are not intended to limit the scope of the claims. Instead, they merely illustrate examples of different embodiments of the disclosed technology. Detailed Implementation

[0025] the term

[0026] The term "coupling" is used in an operational sense and is not limited to direct or indirect coupling. "Coupled to" is generally used to mean direct coupling, while "coupled with" is generally used to mean both direct and indirect coupling. In electronic systems, "coupling" can refer to a configuration that allows information, signals, data, or physical quantities (such as electrons) to flow between two elements coupled to or with each other. In some cases, the flow can be unidirectional; in others, it can be bidirectional or multidirectional. Coupling can be electrostatic (in this context, it means there is a direct electrical connection), capacitive, inductive, electromagnetic, optical, or any other process permitted by physical means.

[0027] A “processor” includes any suitable hardware and / or software system, mechanism, or component that processes data, signals, or other information. A processor may include a system having a general-purpose central processing unit, multiple processing units, a dedicated circuit system for implementing functionality, or other systems. Processing is not necessarily geographically or temporally limited. For example, a processor may perform its functions “in real-time,” “offline,” or in “batch mode.” Parts of the processing may be executed at different times and locations through different (or the same) processing systems. Examples of processing systems may include servers, clients, end-user devices, routers, switches, network storage devices, etc. A “computer” can be any processor that communicates with memory. Memory can be any suitable processor-readable storage medium, such as random access memory (RAM), read-only memory (ROM), a magnetic disk or optical disk, or other tangible medium suitable for storing instructions to be executed by the processor.

[0028] As used herein, the term “and / or” should be interpreted as meaning one or more items. For example, the phrase “A, B and / or C” should be interpreted as meaning any one of the following: A only, B only, C only, A and B (but no C), B and C (but no A), A and C (but no B), or all of A, B and C. As used herein, the phrase “at least one” should be interpreted as meaning one or more items. For example, the phrase “at least one of A, B and C” or the phrase “at least one of A, B or C” should be interpreted as meaning any one of the following: A only, B only, C only, A and B (but no C), B and C (but no A), A and C (but no B), or all of A, B and C. As used herein, the phrase “one or more” should be interpreted as meaning one or more items. For example, the phrase “one or more of A, B and C” or the phrase “one or more of A, B or C” should be interpreted as meaning any one of the following: A only, B only, C only, A and B (but no C), B and C (but no A), A and C (but no B), or all of A, B and C.

[0029] As used in the description herein and throughout the following claims, the terms "a," "an," and "the" include plural references unless the context clearly specifies otherwise. Furthermore, as used in the description herein and throughout the following claims, "in" means both "in" and "on," unless the context clearly specifies otherwise.

[0030] AC - Alternating current - Current that reverses its direction regularly or irregularly.

[0031] DC - Direct Current - Current that flows in only one direction.

[0032] DAC (Digital-to-Analog Converter)

[0033] DMOS - Double-diffused MOSFET

[0034] IC - Integrated Circuit - This can be a monolithic integrated circuit, that is, a single semiconductor die including circuitry, or it can be a multi-chip module including multiple semiconductor dies in a single package and may also include a substrate on which the dies are mounted, as well as other electronic devices.

[0035] IGBT - Insulated Gate Bipolar Transistor

[0036] Lockout duration - The time span during which the electronic protection system does not reconnect the load to the untreated mains power supply after the load has been disconnected, allowing the load to recover, for example, through cooling.

[0037] MOSFET - Metal-Oxide-Semiconductor Field-Effect Transistor.

[0038] Implementation

[0039] Figure 1 A low-cost electronic protection system 100 in an embodiment of the disclosed technology is illustrated. Line rail 101 and neutral rail 102 of the mains power line provide an external, unprocessed supply voltage to a load 103. To protect the load 103 from excessive changes in the external, unprocessed supply voltage, electronic protection circuitry 104 may decouple the load 103 from line rail 101 using a power switch 105. The external, unprocessed supply voltage may be, for example, the 110V, 60Hz AC supply voltage commonly found in the United States, the 230V, 50Hz AC supply voltage commonly found in Europe, or any other AC voltage. Embodiments may provide protection against overvoltage, undervoltage, overcurrent, or any combination thereof. The load 103 may be or include any part of an electronic system that typically uses mains power or any other external, unprocessed supply voltage. For example, the load 103 may include a rectifier bridge that rectifies the mains supply voltage to derive a DC or DC supply voltage. The electronic protection circuit 104 can be implemented in any form, including as a monolithic integrated circuit (single-die IC), as a multi-chip module (MCM) comprising multiple dies placed on a substrate and packaged as a single device, as a printed circuit board (PCB) having both monolithic and discrete devices, and so on. Embodiments may have a power switch 105 external to or internal to the electronic protection circuit 104. Some embodiments use a single power switch 105, while other embodiments may use multiple power switches, and / or a switch neutral rail 102 to replace or supplement the line rail 101. The power switch 105 can be or includes any suitable electronic switch, including but not limited to IGBTs, bipolar transistors, MOSFETs, superjunction MOSFETs, DMOS transistors, thyristors, etc.

[0040] Generally, the electronic protection circuit 104 operates at a circuit supply voltage much lower than the external unprocessed supply voltage between the line rail 101 and the neutral rail 102. This lower circuit supply voltage can be derived from the external unprocessed supply voltage at very low cost, for example, using diode Dsupply 121, resistor Rsupply 122, and capacitor Cshunt 123, as shown. However, this combination can act as a current source rather than a voltage source, delivering a current Isupply whose magnitude is directly dependent on the external unprocessed supply voltage. The current Isupply also depends on the internal operation of the electronic protection circuit 104, and any change in its internal operation will result in a change in the supply voltage received by the electronic protection circuit 104, which will affect threshold detection and introduce instability. As described in this document, the implementation prevents instability. Resistor Rsupply 122 typically has a high value, making the current Isupply very small and allowing the electronic protection system 100 to operate with high efficiency.

[0041] To sense the occurrence of overvoltage (the positive or negative peak amplitude of an external unprocessed supply voltage is too high), and / or to sense the occurrence of undervoltage (the positive or negative peak amplitude of an external unprocessed supply voltage is too low), the electronic protection circuit 104 senses the external unprocessed supply voltage via resistor Rsense 124. This resistor typically has a high value, so only a small amount of current enters the electronic protection circuit 104 at its sensing terminal.

[0042] To prevent glitches caused by the power switch 105 interrupting the current or reconnecting the current to the load 103, the implementation switches when there is only a small current or no current flow. This is expected to occur at twice the trunk frequency, for example, 100 or 120 times per second. Figure 1 One method for detecting this "zero crossing" is described, in which the instantaneous voltage across power switch 105 is sensed using resistors Rzero1 125 and Rzero2 126. Switching is safe when there is no voltage difference. Besides... Figure 1 Implementations other than those depicted can sense zero crossings at other locations, for example, see later reference. Figure 5 As shown, or a single zero-crossing sensing input can be used.

[0043] Figure 2A A summary curve 200 shows the supply current drawn by the electronic protection system as a function of the mains voltage. Its normal operating range is between V... under and V overWithin this range, the electronic protection system must maintain the connection between the mains voltage rail and the load it protects. Connections outside this range are not permitted. For reliable operation, the electronic protection system needs to operate in conjunction with a threshold voltage V. min The associated sufficient supply voltage and sufficient supply current. In some implementations, it may not be necessary to explicitly define V. under And V min Effective dual action as V under Other implementations may not explicitly define V. over And the operation focuses on V min and V under .

[0044] Electronic protection system in V under and V over The intermediate hysteresis is used to avoid the effects of transition instability. Once the main voltage crosses V... under or V over Hysteresis will change those threshold voltages to ensure that decisive crossings are protected from noise below a certain margin, the size of which is determined by the size of the hysteresis.

[0045] To ensure safety and prevent noise and transition instability, the allowable range (this range is between V) is... under and V over The voltage (between) must be widened when the main line voltage is within it, and narrowed when the main line voltage is outside it.

[0046] Currently in V under and V over The nonlinearity used can reduce or reverse the width of the built-in hysteresis, leading to instability. Three critical voltages are worth noting: V min (Region I), V under (Area II) and V over (Region III). In each of those regions, the internal mode of the electronic protection system is different, and different circuits can be active. Therefore, the current, as a function of the line voltage, changes non-linearly around three thresholds. Due to the small power budget of the electronic protection system, relatively large changes in current lead to changes in the internal voltage levels, including those used to determine the threshold level V. under and V over The reference voltage. This can create positive feedback loops and instability.

[0047] Discontinuities outside regions I, II, and III do not present this problem and are unrelated to stability. Regions i (no operation), ii (undervoltage protection), iii (normal operation), and iv (overvoltage protection) can have any shape, including discontinuities and nonlinearities, without increasing the problem. Furthermore, with... Figure 2AThe currents in regions i, ii, iii, and iv may be higher or lower than those shown, their relative magnitudes may differ (e.g., the current in region iii may be lower than the currents in regions ii and iv), and their shapes may differ from the straight line segments shown in regions i to iv.

[0048] During power-on and power-off cycles, the main line voltage passes through V. min (Region I) where the electronic protection system lacks sufficient voltage and / or current to operate. In this Region I, it is equally important to recognize that a rapid rise in line voltage will cause different conditions than a slow rise. This is because the electronic protection system has its own internal stability in operating power. Therefore, the line voltage sensed for normal operation can reach its terminals before the electronic protection system is fully energized. On the other hand, the electronic protection system may only de-energize after it senses a sudden removal of the line voltage.

[0049] Figure 2B Shown in V min At this point, the current can gradually increase by 210 (detail I(a)) or gradually decrease by 220 (detail I(b)). If the current gradually decreases, or is continuous, then a negative feedback loop exists, and the circuit is stable. If the current gradually increases, then a positive feedback loop exists, and the circuit is unstable. Therefore, detail I(a) has inherent instability, and gradually increasing by 210 must be prevented. The implementation must ensure that at V min The electronic protection system must have sufficient current. Otherwise, the effects of nonlinearity will increase significantly, leading to greater instability.

[0050] Figure 2C Shown in V under At this point, the current can increase by 230 or decrease by 240, depending on the exact internal function of the electronic protection system implementation. If it increases V under Therefore, increasing (details II(a)) is inherently unstable, while decreasing V is not. under Then increasing (detail II(a)) is inherently stable. If it decreases V under Therefore, decreasing (details II(b)) is inherently unstable, while increasing V is not. under Therefore, reducing (details II(b)) is inherently stable.

[0051] Implementations without explicit undervoltage protection may have or lack the ability to protect against changes in line voltage (noise) and positive feedback loops caused by current nonlinearity. If it lacks this capability, then undervoltage protection must be built in to ensure stability.

[0052] Figure 2D Shown in Vover The current can be reduced by 250 (details III(a)) or increased by 260 (details III(b)). At the start of overvoltage protection, the permissible range must be narrowed, or more specifically, V over It must be lowered. If reduced by 250 (details III(a)), the threshold voltage V is lowered. over The circuit is inherently stable, but if the threshold voltage is increased, the circuit may become unstable. Similarly, if 260 (details III(b)) is increased, the threshold voltage V decreases. over If the voltage increases, the circuit will become unstable, and if it increases the voltage... over Therefore, it is inherently stable.

[0053] The implementation can be carried out at three threshold voltages V min V under , and V over The circuit can switch one or more dummy currents on or off. This is done in a circuit where... Figure 3-3 As shown in the diagram. They can further reduce the current flowing out of the pins of the electronic protection system IC by using external filtering, such as... Figure 6 As shown in the image.

[0054] Figure 3The illustration shows a first example electronic protection circuit 300 in an embodiment of the disclosed technology. The electronic protection circuit 300 may be an IC and includes a power supply terminal 310, a common terminal 312, at least one zero-crossing detector terminal 314, a sensing terminal 316, and a switching terminal 318 to couple the electronic protection circuit 300 to an external device to form an electronic protection system. The electronic protection circuit 300 also includes a zero-crossing detector 320, a range detector 330, a switch driver 340, a control unit 350, and a one-bit dummy DAC 360 having a DAC switch 370 and a dummy resistor 375. Embodiments may also include a latch-up timer 335 coupled between the range detector 330 on one side and the control unit 350 and dummy DAC 360 on the other side. In some embodiments, the dummy DAC 360 may have a higher resolution than one bit and include additional switched dummy resistors. In other embodiments, the dummy DAC 360 includes one or more switched current sources instead of one or more switched dummy resistors. Power supply terminal 310 receives power supply current, at least a portion of which returns via common terminal 312, and any remaining portion may flow out of electronic protection circuit 300 as one or more operating currents via any other terminal. In some embodiments, or at certain times, the operating current may have a negative sign, i.e., flowing into electronic protection circuit 300 and out of it via common terminal 312. Power supply terminal 310 uses power supply current to generate any desired internal voltage and current sources and voltage and current references, and generally distributes power supply current among circuits within electronic protection circuit 300, including zero-crossing detector 320, range detector 330, switch driver 340, control unit 350, and dummy DAC 360.

[0055] Zero-crossing detector 320 senses when an external current reverses direction, i.e., crosses zero, via at least one of its zero-crossing detector terminals 314. For example, an embodiment may monitor an external unprocessed supply voltage of 230V AC, where the trunk frequency is 50Hz. The external unprocessed supply voltage may be sinusoidal, and the delivered trunk current may cross zero at the top and bottom of the voltage sine and reverse direction. To achieve this, an embodiment of zero-crossing detector terminal 314 may include a differentiator whose input receives a fixed portion of the external unprocessed supply voltage and detects the timing of the top and bottom of the sine when the output of the differentiator changes from negative to positive, or vice versa, i.e., a zero-crossing. Zero-crossing detector terminal 314 provides zero-crossing timing information to control unit 350, which may include timing circuitry, combinational logic, a state machine, a lookup table, a hardwired processor, and / or a programmable processor.

[0056] In another implementation, the zero-crossing detector 320 may have two zero inputs, such as Figure 1 As shown, the zero-crossing of the current is detected by measuring, for example, the voltage across an external power switch. If the external power switch is a solid-state device, its on-resistance will likely be tens to hundreds of milliohms, and any current flowing through it will produce a voltage difference whose polarity is easily measurable.

[0057] Within the range, detector 330 senses via sensing terminal 316 whether an external unprocessed supply voltage is within or outside the permissible range, or whether the absolute value of the external unprocessed supply voltage is within or outside the permissible range. The permissible range can be widened or narrowed; that is, the permissible range can have hysteresis. Once an implementation determines that the external unprocessed supply voltage is outside the permissible range, the permissible range becomes narrower, and once an implementation determines that the external unprocessed supply voltage is within the permissible range, the permissible range becomes wider. Widening and narrowing the permissible range can provide stability around the switching time when naturally occurring noise may otherwise cause unstable transitions from one state to another. An implementation can determine that an external unprocessed supply voltage is outside the permissible range by comparing the peak level or absolute peak level of the external unprocessed supply voltage with overvoltage thresholds and undervoltage thresholds. When it becomes higher than the overvoltage threshold or lower than the undervoltage threshold, then it is outside the permissible range, and an implementation can narrow the permissible range by lowering the overvoltage threshold and / or raising the undervoltage threshold, respectively. Conversely, when it falls below the overvoltage threshold or rises above the undervoltage threshold, it is within the permissible range, and implementations can widen the permissible range by raising the overvoltage threshold and / or lowering the undervoltage threshold. The range detector 330 forwards a signal to the control unit 350, including the result of the range detection and the timing of any changes in the detection result. In an implementation of the electronic protection circuit 300, it also uses the result and its timing to switch the DAC switch 370. In one implementation, it allows current through the dummy DAC 360 as long as the external unprocessed supply voltage is within the permissible range, and stops current through the dummy DAC 360 when the external unprocessed supply voltage is outside the permissible range. In another implementation, it allows current through the dummy DAC 360 as long as the external unprocessed supply voltage is outside the permissible range, and stops current through the dummy DAC 360 when the external unprocessed supply voltage is within the permissible range. In some implementations, the size of the dummy resistor is programmable. Therefore, the current through the dummy DAC 360 can compensate for changes in the supply current through the power supply terminal 310 between two modes: within and outside the range.

[0058] Some implementations include a lockout timer 335. The lockout timer 335 has a lockout duration, which can be programmable, for example, set via a register, or configurable, for example, via the capacitance of a lockout time capacitor externally connected to lockout capacitor terminal 315, or via other means such as a resistance value, IC bonding options, voltage applied to external IC terminals, the contents of non-volatile or one-time programmable memory, IC mask options, and any other methods known in the art. If the lockout duration is configured by a lockout capacitor value, then the lockout timer 335 can time out after one or more cycles of charging the lockout capacitor. The lockout timer 335 ensures that out-of-range signals from the range detector are always delivered for at least the lockout duration. This allows for some thermal recovery time for external loads after the electronic protection circuit disconnects the load from the mains power line following the detection of a hazardous condition. If the lockout timer 335 receives an out-of-range signal from the range detector 330, then in some implementations, the lockout timer 335 ensures that its output signal replicates the out-of-range signal for at least the lockout duration, while in other implementations, the lockout timer 335 ensures that its out-of-range output signal continues beyond the end of its out-of-range input signal for at least the lockout duration. At other times, the latch timer 335 copies the input signals within its range to the output.

[0059] The switch driver 340 includes a buffer to drive at least one power switch, such as an IGBT, bipolar transistor, MOSFET, superjunction MOSFET, DMOS transistor, thyristor, etc., wherein one or more power switches couple an external unprocessed supply voltage to or to a load to be protected. The switch driver 340 may also include a timing circuitry, for example, to operate one or more power switches with one or more delays, which may be programmable.

[0060] The control unit 350 controls the switch driver 340 based on information it receives from the zero-crossing detector 320 and the range detector 330. Specifically, its function includes determining from the range detector 330 when an external unprocessed supply voltage exceeds the range, then waiting for a signal from the zero-crossing detector 320 indicating that a zero-crossing has occurred, and then instructing the switch driver 340 to turn off the power switch.

[0061] Figure 4A second example electronic protection circuit 400 in an embodiment of the disclosed technology is illustrated. Electronic protection circuit 400 includes all the elements of electronic protection circuit 300, drawn with the same reference numerals. However, in this embodiment, control unit 450, instead of range detector 430, controls dummy DAC 460. Timing is such that control unit 450 modifies dummy DAC 460 no earlier than it receives a change from range detector 430 and no later than it processes a change from zero-crossing detector 420. In this way, electronic protection circuit 300 and electronic protection circuit 400 operate substantially the same, but with the added possibility of controlling the timing and magnitude of the current through dummy DAC 460. Dummy DAC 460 can be implemented using one or more switched dummy resistors, such as... Figure 3 As shown, it can be implemented using a switched current source, or as any other DAC known in the art with current output.

[0062] Figure 3-4 An implementation method that can be easily integrated into a single semiconductor using this technology is described. Figure 5 An example electronic protection system 500 in an embodiment of the disclosed technology is illustrated, including, for example... Figure 3 As shown or as Figure 4 The electronic protection circuit 510 shown is characterized by two input terminals for detecting zero crossings, namely, zero-crossing terminal 514. A And zero-crossing terminal 514B. The electronic protection system 500 operates on neutral rail 520 and line rail 522, applying an external, unprocessed supply voltage between them. In this embodiment, neutral rail 520 is directly coupled to load 528, while line rail 522 is coupled to load 528 via external switches 530 and 540. Electronic protection circuit 510 has a common terminal coupled to a common node 524, which is coupled between external switches 530 and 540. Diode 531 ensures that the circuit can be energized. When line rail 522 is positive and both external switches 530 and 540 are off, diode 541 allows a continuous common conduction path back to neutral rail 520. Electronic protection circuit 510 receives its supply current via, for example, resistor Rsupply. Its supply terminal can be shunt to common node 524 using a decoupling capacitor Cshunt (e.g., as shown). This embodiment senses overvoltage and undervoltage conditions via sensing terminal 516, which is coupled to the neutral rail 520 via, for example, a large resistor Rsense. This embodiment senses zero crossings by detecting the presence of a zero voltage difference between the sensing rail 522 and the load node 526. Sensing is accomplished via two large resistors Rzero1 and Rzero2, one of which protects the zero-crossing terminal 514. Aand zero-crossing terminal 514 B If an embodiment of the electronic protection circuit 510 includes a lockout timer, it may have a lockout capacitor terminal 515 for connection to an external lockout capacitor 527 configured with a lockout duration.

[0063] In the example electronic protection system 500, the neutral rail 520 may be within an allowable range while the electronic protection circuit 510 is still energized. Charging the Cshunt via Rsupply to a supply voltage sufficient for the electronic protection circuit 510 to operate fully takes time, while the voltage at the neutral rail 520 is immediately sensed via Rsense. When the supply voltage to the electronic protection circuit 510 is insufficient, external switches 530 and 540 are turned off (in appropriate functional implementations). When a sufficient supply voltage is reached, these switches are turned on because the range detector senses that the unprocessed external supply voltage is within an allowable range.

[0064] It is possible that the external unprocessed supply voltage begins slowly compared to the time it takes to charge the Chaunt via the Rsupply, or that the external unprocessed supply voltage is otherwise outside the acceptable range. Both external switches 530 and 540 are disconnected. The allowable range narrows. After reaching the undervoltage threshold, the allowable range widens, and external switches 530 and 540 couple line rail 522 to load node 526, thereby applying the external unprocessed supply voltage to load 528. This implementation maintains this state until the external unprocessed supply voltage drops below or rises above the widened allowable range.

[0065] Figure 5 This describes one of several architectures in which the electronic protection circuit 510 can be used to create an electronic protection system. Other embodiments may couple the common terminal of the electronic protection circuit 510 to the neutral rail 520 instead of the line rail 522; they may use switches to disconnect the two sides of the load (in this case, load 528) from the main power supply rail; and they may use circuitry other than diodes, Rsupply, and Cshunt to power the electronic protection circuit 510. All such variations are within the scope of this disclosure. For practical purposes, Figure 5 The example implementations described may be one of the lowest-cost implementations. This is why sometimes it may be necessary to... Figure 6 The circuitry within the circuitry is intended to further reduce and / or eliminate the cause of positive feedback problems.

[0066] Figure 6The illustration shows details 600 of a filter 680 that provides additional power supply stability in an implementation of the disclosed technology. This embodiment uses the filter 680 to reduce the current through the pins of the electronic protection IC 610, thereby reducing the magnitude of nonlinearity in its supply current as a function of an external, unprocessed voltage, and thus reducing positive feedback caused by nonlinearity. As long as the total effect of any positive feedback is small relative to the magnitude of hysteresis within permissible limits, the transition occurring at the threshold voltage can be stable and decisive. Electronic protection circuits generally need to sense both positive and negative signals. To easily do this, the IC is required to have positive and negative supply voltages referenced to a common node. However, a low-cost alternative is to use an IC with a single power supply, for example, using a positive supply terminal and a common terminal. A reference voltage terminal that outputs a reference voltage higher than the common terminal potential but lower than the supply terminal potential can then be used as a reference for sensing positive and negative overvoltage and undervoltage conditions. The reference voltage terminal alternately supplies and absorbs sensing current during operation, depending on the instantaneous voltage of the unprocessed supply voltage, while sensing whether the unprocessed supply voltage is within range. The magnitude of the sensed current can be significant compared to the total supply current consumed by the IC, which can compromise its operational stability. Figure 6 The system includes an electronic protection IC 610 with a sensing terminal 616 and a reference voltage terminal 617. The electronic protection IC 610 draws its supply current from the neutral rail 620 via a rectifier diode and resistor Rsupply or via any other means to provide a supply voltage lower than the maximum positive voltage on the neutral rail 620, and returns the supply current to the line rail 622 via an external switch 630 (or a parallel rectifier diode) and a common node 624. As mentioned, even though the sensing terminal 616 may have high impedance and may not affect the supply current, the reference voltage terminal 617 may have low impedance and can provide and draw current. A filter 680 divides the voltage between the neutral rail 620 and the reference voltage terminal 617 via voltage dividers R 681 and R 682. The voltage division at the sensing terminal 616 is approximately equal to:

[0067]

[0068] Without resistor 683 and capacitor 684, the electronic protection IC 610 would draw current from or supply current to reference voltage terminal 617, a current equal to the voltage across R1+R2 divided by R1+R2. As mentioned above, this can be unacceptable, and resistor 683 and capacitor 684 provide protection by drawing a large portion of this current from common node 624 at the line frequency. For example, if the impedance of capacitor 684 at the line frequency is equal to 10% of the resistance of resistor 683, then the amount of current supplied to or drawn by reference voltage terminal 617 is reduced by 90%.

[0069] Figure 7 The illustration depicts a method 700 for protecting against overvoltage and undervoltage conditions in an embodiment of the disclosed technology. Method 700 includes the following steps, which may be performed in a continuous loop after the first step.

[0070] Step 710 - Using an electronic protection system, decouple the external load from the external unprocessed supply voltage between the line rail and the neutral rail, and initialize the dummy current in the protection IC. The protection IC provides a first switching signal to the switch to decouple the load from the unprocessed supply voltage. The external unprocessed supply voltage may, for example, come from an external mains power supply. The external load may be or include a rectifier bridge or any other device, circuit, or system that needs protection against overvoltage and / or undervoltage. This implementation initializes the dummy current to a first value based on whether the electronic protection system receives sufficient supply voltage and sufficient supply current to operate fully and based on whether the peak value of the unprocessed supply voltage falls within a narrowed allowable range. The allowable range is defined as the range between an overvoltage threshold and an undervoltage threshold. Some implementations monitor one polarity of the unprocessed supply voltage, while others monitor both polarities or the absolute value of the unprocessed supply voltage.

[0071] Step 720 - Determine whether the peak value of the unprocessed supply voltage is within the narrowed allowable range. The embodiment provides an unprocessed supply voltage sensing signal to a protection IC, which determines whether the peak value of the unprocessed supply voltage is within the narrowed allowable range by comparing the unprocessed supply voltage detection signal with a first window threshold.

[0072] Step 730 - After determining that the peak value of the unprocessed supply voltage is not within the allowable range of the narrowing, return to step 720.

[0073] Step 740 - After determining that the peak value of the unprocessed supply voltage is within the narrowed allowable range, the allowable range is widened, and then the first zero-crossing is waited for. To widen the allowable range, the implementation may raise the overvoltage threshold and / or lower the undervoltage threshold to a second window threshold. The first zero-crossing may be defined as the moment when the unprocessed supply voltage equals zero or as the moment when the voltage on the switch equals zero. This implementation may wait for zero-voltage time when coupling the load to the unprocessed supply voltage to avoid high-voltage transients.

[0074] Step 750 - Change the dummy current to a second value, and then couple the load to the unprocessed supply voltage. The second value of the dummy current is a value to prevent positive feedback, which would significantly narrow the allowable range during load coupling with the unprocessed supply voltage. The protection IC provides a second switching signal to the switch to couple the load to the unprocessed supply voltage.

[0075] Step 760 - Determine if the peak value of the unprocessed supply voltage is outside the widened allowable range. The protection IC compares the unprocessed supply voltage sensing signal with a second window threshold.

[0076] Step 770 - After determining that the peak value of the unprocessed supply voltage is not outside the widened allowable range, return to step 760.

[0077] Step 780 - After determining that the peak value of the untreated supply voltage is outside the widened allowable range, the allowable range is narrowed, and then the system waits for the second zero crossing. To narrow the allowable range, the implementation may lower the overvoltage threshold and / or raise the undervoltage threshold. The second zero crossing is defined as the moment when the current delivered by the untreated supply voltage equals zero. In an alternating current (AC) environment, this is the moment when the current changes direction. This implementation waits for the zero-current time to avoid high-voltage transients caused by interrupting the load with the untreated supply voltage, where current can pass through any inductive impedance associated with the electronic protection system or the load.

[0078] Step 790 - First, the dummy current is changed to a third value, and then the load is decoupled from the unprocessed supply voltage. The third value of the dummy current is a value to prevent positive feedback, which would cause a significant widening of the allowable range narrowed during the decoupling of the load from the unprocessed supply voltage. The implementation can then return to step 720.

[0079] Considerations

[0080] Although this description has been given with reference to specific embodiments thereof, these specific embodiments are merely illustrative and not limiting. For example, Figure 3-4 The electronic protection circuit is described as operating with a positive supply voltage at the reference common terminal. However, all parts of the disclosed technology can be equally applied to electronic protection circuits operating with a negative supply voltage at the reference common terminal. Furthermore, the given example illustrates a circuit using a line rail as a ground reference, while other embodiments may use a neutral rail as a ground reference. The example provides supply current to the electronic protection system via a resistor, while other embodiments may use a switching power supply to power the fuse circuit. Some embodiments may provide only overvoltage protection, while others may provide only undervoltage protection or both overvoltage and undervoltage protection. Figure 3-4The illustration shows an implementation where a power switch is located outside an integrated circuit controlled by an electronic protection system. However, some implementations may include a power switch.

[0081] Except where at least some of these features and / or steps are mutually exclusive combinations, all features disclosed in the specification, including the claims, abstract, and drawings, and all steps in any disclosed method or process, may be combined in any combination. Unless otherwise expressly stated, each feature disclosed in the specification, including the claims, abstract, and drawings, may be replaced by an alternative feature for the same, equivalent, or similar purpose.

[0082] While this description has been given with respect to specific embodiments thereof, these specific embodiments are merely illustrative and not limiting. For example, many operations can be implemented on a printed circuit board (PCB) using off-the-shelf devices, in a system-on-a-chip (SoC), application-specific integrated circuit (ASIC), programmable processor, or in a programmable logic device (such as a field-programmable gate array (FPGA)) without requiring at least part of dedicated hardware. All such variations and modifications are to be considered within the scope of this disclosure, the nature of which will be determined by the foregoing description.

[0083] The circuits of a particular implementation can be implemented using any suitable technique used to manufacture electronic devices, including CMOS, FinFET, BiCMOS, bipolar, JFET, MOS, NMOS, PMOS, HBT, MESFET, etc. Different semiconductor materials can be used, such as silicon, germanium, SiGe, GaAs, InP, GaN, SiC, graphene, etc. The circuits can have single-ended or differential inputs and single-ended or differential outputs. The terminals of the circuits can be used as inputs, outputs, or both, or in a high-impedance state, or they can be used to receive power, ground references, reference voltages, reference currents, or others. Although the physical processing of signals can be presented in a specific order, this order can be changed in different specific implementations. In some specific implementations, multiple elements, devices, or circuits shown in sequence in this specification can operate in parallel.

[0084] The routines for a particular implementation can be implemented using any suitable programming language, including C, C++, Java, JavaScript, compiled languages, interpreted languages ​​and scripting languages, assembly languages, machine languages, etc. Different programming techniques can be employed, such as procedural or object-oriented programming. The methods implemented in the routines can be executed on a single-processor device or a multiprocessor system. Although the steps, operations, or calculations can be presented in a specific order, this order can vary in different specific implementations. In some specific implementations, multiple steps shown in sequence in this specification can be performed simultaneously.

[0085] Specific implementations may be implemented in a tangible, non-transitory computer-readable storage medium for use by or in conjunction with an instruction execution system, apparatus, board, or device. Specific implementations may be implemented in the form of control logic in software, hardware, or a combination of both. When executed by one or more processors, the control logic may be operable to perform those described in the specific implementation. For example, a tangible, non-transitory medium such as a hardware storage device may be used to store control logic that may include executable instructions.

[0086] Specific implementations can be achieved using programmable general-purpose digital computers, application-specific integrated circuits, programmable logic devices, field-programmable gate arrays, optical, chemical, biological, quantum, or nanoengineered systems, etc. Other components and mechanisms can be used. Generally, the functionality of a particular implementation can be achieved by any means known in the art. Distributed network systems, components, and / or circuits can be used. Cloud computing or cloud services can be employed. Data communication or transmission can be wired, wireless, or via any other means.

[0087] It will also be recognized that one or more of the elements depicted in the figures / figures may also be implemented in a more separate or integrated manner, or even removed or rendered inoperable in some cases, as may be useful for a particular application.

[0088] Therefore, although specific embodiments have been described herein, modifications, various changes, and substitutions are intended within the scope of the foregoing disclosure, and it will be appreciated that in some cases, certain features of specific embodiments will be used without corresponding use of other features, without departing from the scope and spirit set forth. Thus, many modifications can be made to adapt specific situations or materials to the basic scope and spirit.

Claims

1. An electronic protection circuit, comprising: The power supply terminal is operable to receive power supply current. A common terminal, operable to return at least a portion of the supply current; A sensing terminal is electrically coupled to a range detector, wherein the range detector is operable to determine whether the peak value of an external unprocessed supply voltage is within an allowable range, wherein the allowable range can be widened in a first state and narrowed in a second state, and wherein the range detector delivers a range detection output signal that signals a condition within or outside the range depending on whether the peak value of the external unprocessed supply voltage is within the allowable range. One or more zero-crossing detection input terminals are electrically coupled to a zero-crossing detector, wherein the zero-crossing detector is operable to determine the time of a first zero-crossing and the time of a second zero-crossing, wherein the time of the first zero-crossing is the time of zero-crossing detected after the range detection output terminal signals a condition within the range, and the time of the second zero-crossing is the time of zero-crossing detected after the range detection output terminal signals a condition outside the range. The output terminal of the switch driver is coupled to the output terminal of the switch driver. The control unit has a first input coupled to the output of a zero-crossing detector, a second input coupled to the output of a range detection detector, and an output coupled to the input of a switch driver, wherein the control unit is configured to change the switch driver to the ON state from the time of the first zero crossing until the time of the second zero crossing; as well as A dummy DAC has a current output terminal operable to supply a dummy current that prevents instability caused by positive feedback during the transition from a first state to a second state and during the transition from a second state to a first state, wherein the dummy current flows from the power supply terminal to the common terminal through the dummy DAC.

2. The electronic protection circuit of claim 1 further includes a lockout timer coupled between the range detection output and the first input of the control unit, wherein the lockout timer is operable to transmit a range detection output signal after the range detection output signals a condition outside the range, and to transmit a modified range detection output signal after a lockout duration following the signaling of a condition within the range at the range detection output, wherein the lockout duration is configurable.

3. The electronic protection circuit of claim 2, wherein the lock duration is configured by the value of the lock capacitor, and the lock timer times out after one or more cycles of charging the lock capacitor.

4. The electronic protection circuit as described in claim 2, wherein: The latch timer times out after one or more clock cycles; and The lock duration is configured by at least one of the following: IC bonding options; The voltage applied to the IC pins; Register value; The contents of volatile memory; The contents of non-volatile memory; The contents of the one-time programmable memory; or IC mask options.

5. The electronic protection circuit as described in claim 1, wherein, When the external unprocessed supply voltage is outside the allowable range, the allowable range is narrowed; when the external unprocessed supply voltage is within the allowable range, the allowable range is widened.

6. The electronic protection circuit as claimed in claim 1, wherein the dummy DAC comprises one or more switches and a dummy resistor.

7. The electronic protection circuit as claimed in claim 1, wherein the dummy DAC includes one or more switching current sources.

8. The electronic protection circuit as claimed in claim 1, wherein the output level of one or more dummy DACs is programmable.

9. The electronic protection circuit as claimed in claim 1, wherein the range detection output signal controls the dummy DAC.

10. The electronic protection circuit of claim 1, wherein the control unit controls the dummy DAC.

11. The electronic protection circuit as described in claim 1, further comprising: An active clamping circuit coupled between an input terminal and a common terminal, the active clamping circuit comprising: The first buffer is configured to clamp the input terminal to the supply voltage when the voltage on the input terminal is higher than a first margin relative to the supply voltage, and to clamp the input terminal to the common terminal when the voltage on the input terminal is lower than a second margin relative to the common terminal potential.

12. A method for protecting a load from overvoltage or undervoltage conditions in an untreated supply voltage between the line rail and the neutral rail, comprising: (a) From the protection integrated circuit IC, a first switching signal is provided to the switch to decouple the load from the unprocessed supply voltage, wherein the switch is coupled between the load and one of the line rail and the neutral rail; (b) In the protection IC, the dummy current is initialized to the first value; (c) Provide an unprocessed supply voltage sensing signal to the protection IC, and in the protection IC, determine whether the peak value of the unprocessed supply voltage is within the narrowed allowable range by comparing the unprocessed supply voltage sensing signal with a first window threshold; (d) After determining that the peak value of the unprocessed supply voltage is not within the allowable range of the narrowing, return to step (c); (e) After determining that the peak value of the unprocessed supply voltage between the line rail and the neutral rail is within the narrowed allowable range, the narrowed allowable range is widened to the widened allowable range defined by the second window threshold. (f) Waiting for the first zero-crossing in the zero-crossing detector input signal of the protection IC; (g) Change the dummy current to the second value; (h) Provide a second switching signal from the protection IC to the switch to couple the load to the unprocessed supply voltage; (i) In the protection IC, it is determined whether the peak value of the unprocessed supply voltage is outside the widened allowable range by comparing the unprocessed supply voltage sensing signal with a second window threshold; (j) After determining that the peak value of the unprocessed supply voltage is not outside the widened allowable range, return to step (i); (k) After determining that the peak value of the unprocessed supply voltage is outside the widened allowable range, narrow the widened allowable range to the narrowed allowable range; (l) Wait for the second zero crossing; (m) Change the dummy current to the third value; as well as (n) Provide a first switching signal to the switch to decouple the load from the unprocessed supply voltage.

13. The method of claim 12, further comprising: After determining that the peak value of the unprocessed supply voltage is outside the widened allowable range, a lockout duration is waited for at least a lockout duration before allowing the load to couple to the unprocessed supply voltage, wherein the lockout duration is configurable.

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