Current protection system
By introducing a shunt subsystem and a comparator subsystem into the current protection system, and using an offset-compensated operational amplifier to accurately measure the shunt voltage, the problem of insufficient measurement accuracy for low shunt voltage is solved, and effective protection against high current is achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- INFINEON TECHNOLOGIES AG
- Filing Date
- 2025-11-20
- Publication Date
- 2026-05-22
AI Technical Summary
In current protection systems, the shunt voltage is low and the measurement accuracy is insufficient, making it difficult to effectively protect the load from overcurrent.
The system employs a shunt subsystem and a comparator subsystem, including a first switch, a shunt resistor, an offset-compensated operational amplifier, and a control unit, to achieve current protection by accurately measuring the shunt voltage and controlling the switch.
It achieves high-precision protection for small currents, reduces the heating of shunt resistors, can switch currents up to 1000A, and quickly detects overcurrent and limits or trips it.
Smart Images
Figure CN122073369A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of current protection systems. It also relates to methods, systems, and uses for protecting loads from overcurrent. Background Technology
[0002] In at least some current protection systems, shunt resistors are used to sense the current of interest, such as the current through a switch. For current protection systems with small maximum permissible currents and / or for shunt resistors with very low resistance, the shunt voltage across the shunt resistor can be very low. Measuring such low shunt voltages with sufficient accuracy is a difficult task. Summary of the Invention
[0003] One aspect relates to a current protection system including a shunt subsystem arranged between the input and output of the current protection system. The shunt subsystem includes a first switch and a shunt resistor, the first switch and the shunt resistor being arranged in series. The current protection system also includes a comparator subsystem arranged in parallel with the shunt resistor, the comparator subsystem being configured to compare the shunt voltage across the shunt resistor with a reference voltage. The comparator subsystem includes an offset-compensated operational amplifier and a control unit arranged between the output of the comparator subsystem and a first control input of the first switch.
[0004] A current protection system can be configured to protect switches and / or loads that can be controlled by a switch. The load can be arranged in series with the switch. The current protection system can be used for DC current, AC current, and / or currents of other waveforms. The current protection system includes a shunt subsystem. The shunt subsystem is arranged between the input and output of the current protection system. The shunt subsystem includes a first switch and a shunt resistor, wherein the first switch and the shunt resistor are arranged in series. For example, the first switch can be a semiconductor and / or a relay. The resistance of the shunt resistor can depend on the maximum current to be protected by the current protection system. The shunt resistor can be an (ohmic) resistor, a Hall sensor, and / or other device capable of sensing line current.
[0005] A comparator subsystem is arranged in parallel with a shunt resistor, wherein the comparator subsystem is configured to compare the shunt voltage across the shunt resistor with a reference voltage. The comparator subsystem includes an offset-compensated operational amplifier. Due to Ohm's law, the shunt voltage across the shunt resistor is proportional to the current through the shunt subsystem. A similar dependency can be applied to other types of shunt resistors, such as Hall sensors. Therefore, the comparator subsystem is configured to sense the current through the shunt subsystem, i.e., the current through the shunt resistor and the switch, which may also pass through other components arranged in series with the shunt subsystem, such as through a load. Furthermore, a control component is arranged between the output of the comparator subsystem and a first control input to the first switch. The control input to the first switch can be the gate of a FET (field-effect transistor) or the base of a bipolar transistor.
[0006] In particular, by using an offset-compensated operational amplifier (i.e., by keeping the voltage offset of the operational amplifier (op-amp) low), the current protection system can measure voltages like shunt voltages very accurately, even when low (shunt) voltages are to be measured. This high accuracy can be used to provide current protection even for small currents, and / or can be used to select small shunt resistors with very low impact on the system to be protected and / or the shunt resistor itself, for example by reducing heat generation in the shunt resistor at high system currents.
[0007] In various embodiments, the current protection system also includes a second switch arranged in parallel with the shunt subsystem. A control unit is positioned between the output of the comparator subsystem and a second control input to the second switch, such that the control unit controls the inputs of both the first and second switches. The first and second switches can be of the same type. The second switch can be designed for higher currents than the first switch. This arrangement also reduces the current through the shunt resistor because the current through the current protection system is divided between the first and second switches. A current proportional to the current through the second switch flows through the shunt subsystem. Therefore, the comparator subsystem is also configured to sense the current through the second switch. This embodiment can allow switching of considerably high currents, for example, up to 10 A in some systems, up to 100 A in others, and even up to 1000 A in still others.
[0008] In various embodiments, the offset-compensated operational amplifier is designed as an auto-zero operational amplifier system. The auto-zero operational amplifier system provides offset compensation, particularly high-stability offset compensation.
[0009] In various embodiments, the auto-zero operational amplifier is designed as a ping-pong auto-zero operational amplifier system. A ping-pong auto-zero operational amplifier system comprises two essentially identical sub-circuits whose switches alternate periodically. Detailed examples of ping-pong auto-zero operational amplifier systems are provided below.
[0010] In some embodiments, the auto-zero operational amplifier includes a differential pair of semiconductor devices. The source of a first semiconductor device is connected to a reference voltage, and its gate and drain are connected to a reference current. The source of a second semiconductor device is connected to a shunt voltage via a first phase switch, the gate of the second semiconductor device is connected to the gate of the first semiconductor device, and the drain of the second semiconductor device is connected to the reference current. Furthermore, a first amplifier switch is disposed between the shunt voltage and the second semiconductor device, and a second amplifier switch is disposed between the sources of the first and second semiconductor devices. The auto-zero operational amplifier further includes: a third amplifier switch, the first end of which is connected to the drain of the second semiconductor device; a third semiconductor device, the gate of which is connected to a second end of the third amplifier switch; and a fourth semiconductor device, the gate of which is connected to the drains of the second and third semiconductor devices. A first capacitor is disposed at the gate of the third semiconductor device. The auto-zero operational amplifier further includes: a fourth amplifier switch, the first end of which is connected to the drain of a fourth semiconductor device; a fifth semiconductor device, the gate of which is connected to the second end of a third amplifier switch; and a fifth amplifier switch, the first end of which is connected to the drains of the fourth and fifth semiconductor devices, and the second end of which is connected to the output of the auto-zero operational amplifier. A second capacitor is disposed at the gate of the fifth semiconductor device. The semiconductor may be, for example, a FET or a bipolar transistor. Figure 4 An example embodiment of these embodiments is shown below. This embodiment can help avoid operational amplifier saturation problems during offset compensation phase.
[0011] In various embodiments, the first switch and the second switch are MOSFETs (metal-oxide-semiconductor field-effect transistors), NMOS, PMOS, bipolar semiconductors, IGBTs (insulated gate transistors), or relays, such as reed relays.
[0012] In various embodiments, the shunt voltage that can be sensed by the comparator subsystem is less than 1 mV, for example less than 200 μV, for example less than or equal to 50 μV.
[0013] In various embodiments, the control unit includes a current-limiting controllable current source. The controllable current source is configured to be controlled by a semiconductor element disposed at the output of the comparator subsystem. Thus, when the shunt voltage across the shunt resistor is higher than or equal to a first predetermined reference voltage, the current through the first and second switches is limited. Figure 6a An example embodiment of these embodiments is shown.
[0014] In various embodiments, the first predetermined reference voltage has hysteresis. This can be achieved by an operational amplifier with hysteresis, such as a Schmitt trigger. These embodiments can detect the overcurrent condition very quickly when it ends. Figure 7a An example embodiment of these embodiments is shown.
[0015] In various embodiments, the control unit includes a latch whose set input is configured to be set by an operational amplifier. Therefore, the inverting output of the latch is configured to block current through the first switch when the shunt voltage across the shunt resistor is higher than or equal to a second predetermined reference voltage. Figure 5a An example embodiment of these embodiments is shown.
[0016] In various embodiments, the control element includes a switch disposed between the input and output of the control element, wherein the switch is open when the shunt voltage across the shunt resistor is higher than a second predetermined reference voltage. Thus, the tripping function of the current protection system can be implemented. The tripping function can operate additionally or as a replacement for the current limiting function.
[0017] In various embodiments, the control components consist of wires that cause the first and second switches to open when the shunt voltage across the shunt resistor is higher than a third predetermined reference voltage. This can be a very simple implementation for achieving a tripping function, where only the wires connect the output of the offset-compensated operational amplifier to the control input of the first (and, if available, the second) switch.
[0018] One aspect relates to a method for protecting a load from overcurrent. The method includes the following steps: Close the first switch, which is part of a shunt subsystem including the first switch and the shunt resistor. The first switch and the shunt resistor are arranged in series, and the shunt subsystem is arranged in parallel with the load. Sensing the shunt voltage across the shunt resistor; The shunt voltage is compared with a reference voltage using a comparator subsystem, which includes an auto-zero operational amplifier; and When the shunt voltage is higher than or equal to the first predetermined reference voltage, the current through the first switch is limited.
[0019] In various embodiments, the method further includes the following steps: When the shunt voltage across the shunt resistor is higher than or equal to the second predetermined reference voltage, the first switch is disconnected.
[0020] In various embodiments, the method further includes the following steps: Close the second switch, which is arranged in parallel with the shunt subsystem; and When the shunt voltage across the shunt resistor is higher than or equal to the first predetermined reference voltage, the current through the second switch is limited.
[0021] In various embodiments, the method further includes the following steps: When the shunt voltage is higher than or equal to the second predetermined reference voltage, the second switch is disconnected.
[0022] One aspect relates to a system comprising the current protection system described above and / or below. The system also includes a generator, and the system includes at least one load connected in series with the current protection system and the generator. Examples of the generator may include a battery (e.g., a car battery) or a photovoltaic system. The load may be a single load among multiple loads, which may be connected in any topology. The load may be any type of "consumption device." In a car, this may be, for example, a so-called "safety load" of the car (e.g., headlights, engine control, braking, or power steering).
[0023] One aspect relates to the use of current protection systems described above and / or below in automotive systems, particularly for protecting the current protection system itself and / or the vehicle's consumable devices, the motor and / or battery of an electric vehicle, photovoltaic systems and / or their consumable devices.
[0024] It should be noted that the two or more embodiments described above and / or below can be combined to the extent technically feasible.
[0025] To further clarify, this disclosure has been described with the aid of embodiments shown in the accompanying drawings. These embodiments are considered as examples only and are not intended to be limiting. Attached Figure Description
[0026] The attached image depicts:
[0027] Figure 1 and Figure 2 The system according to an embodiment is illustrated schematically;
[0028] Figure 3 -5 schematically illustrates an automatic zeroing operational amplifier according to an embodiment;
[0029] Figure 6-8 schematically illustrates a current protection system according to an embodiment;
[0030] Figure 8 This is a flowchart based on an embodiment. Detailed Implementation
[0031] Figure 1A system according to an embodiment is schematically illustrated. The system includes a current protection system 100 and a load 300. The load 300 is connected to the output 190 of the current protection system 100. Additionally or alternatively, the load 300 may be connected to the input 110 of the current protection system 100. The current protection system 100 includes a shunt subsystem 120 disposed between the input 110 and the output 190 of the current protection system 100. The shunt subsystem 120 includes a first switch M1 and a shunt resistor 140, the first switch M1 and the shunt resistor 140 being arranged in series. The current protection system 100 also includes a comparator subsystem 150 disposed in parallel with the shunt resistor 140. Terminals 151, 152 are disposed at the ends of the shunt resistor 140. The comparator subsystem 150 is configured to convert the shunt voltage U across the shunt resistor 140... sh With reference voltage U ref The comparison is performed. The comparator subsystem 150 includes an offset-compensated operational amplifier 160. The current protection system 100 also includes a control unit 200 arranged between the output 180 of the comparator subsystem 150 and the first control input 121 (gate) of the first switch M1. Therefore, the control unit 200 is based on the shunt voltage U. sh With reference voltage U ref The comparison between the two is used to control the first switch M1. The control unit 200 can, for example, implement tripping and / or current limiting functions.
[0032] Figure 2 The system according to an embodiment is illustrated schematically. Figure 2 The system and Figure 1 The system is similar. The same reference numerals indicate the same... Figure 1 The same or similar parts. Figure 2 and Figure 1 Unlike the additional second switch M2 arranged in parallel with the shunt subsystem 120, the control unit 200 is arranged between the output 180 of the comparator subsystem 150 and the second control input 122 of the second switch M2. In many embodiments, the second switch M2 is designed to control a higher current than the first switch M1. In many embodiments, the second switch M2 is of the same or very similar type to the first switch M1; for example, M1 and M2 are based on the same technology, and / or they may have the same physical layer.
[0033] Figure 3 An auto-zero operational amplifier 160, which is part of a comparator subsystem 150 according to an embodiment, is schematically shown. The auto-zero operational amplifier 160 is arranged between terminals 151, 152 as inputs and terminal 180 as an output (see [link]). Figure 1 and Figure 2The auto-zero operational amplifier 160 includes two nearly identical sub-circuits, each including an operational amplifier (op-amp), namely a first operational amplifier 161 and a second operational amplifier 162. The auto-zero operational amplifier 160 of this embodiment is implemented as a so-called ping-pong auto-zero operational amplifier system.
[0034] The name "ping-pong type" refers to the functional principle of this type of auto-zeroing operational amplifier system: In stage #1, when the first operational amplifier 161 amplifies the signal, the second operational amplifier 162 automatically zeros. In stage #2, the opposite is true; that is, when the second operational amplifier 162 amplifies the signal, the first operational amplifier 161 automatically zeros. The two amplifiers 161 and 162 switch back and forth between stage #1 and stage #2, so the auto-zeroing operational amplifier system 160 can operate continuously as a whole; hence the name "ping-pong type" auto-zeroing operational amplifier. Figure 3 The auto-zeroing operational amplifier 160 in stage #1 is shown. This stage uses the scheme in Table 1, switched by amplifier switches sw11 to sw14 and sw21 to sw24. Note that in Figure 3 Switches SW13 and SW23 are not shown. This is because these switches are located "inside" operational amplifiers 161 and 162, respectively. See also Figure 4 For an exemplary embodiment. Table 1: Automatic Zeroing Scheme
[0035] As another embodiment of the auto-zero operational amplifier 160 Figure 4 A sub-circuit comprising one half (“ping”) of a complete auto-zero operational amplifier is shown. As noted above, the other half (“pong”) is quite similar due to the “ping-pong” function. The auto-zero operational amplifier 160 includes a differential pair of semiconductors M3-1 and M3-2. Semiconductors M3-1 and M3-2 are arranged in a common-gate configuration. Therefore, the gate voltage of M3-2 is the same as the gate voltage of M3-1. The source inputs of M3-1 and M3-2 are connected to a reference voltage U. ref and shunt voltage U sh (See) Figure 1 and Figure 2 M3-1 is in a diode configuration and is connected to the reference current I. ref The series connection generates a constant voltage across its drain-source path because a constant voltage is injected into this path. When the source voltage of M3-1 increases or decreases, the gate voltage of M3-1 increases or decreases by the same amount, respectively. Therefore, when the source voltage of M3-2 is higher than the source voltage of M3-1, the gate-source voltage U of M3-2... GS U below M3-1GS Therefore, the current flowing through M3-2 is less than the current flowing through M3-1. Therefore, the drain voltage of M3-2 is higher than the drain voltage of M3-1 (when the same reference current is used in both branches). Therefore, when the comparator is in the auto-zero phase (sw12 closed, sw11 open), the two source voltages are (essentially) equal, and the two transistors (M3-1 and M3-2) have the same V0. GS Therefore, the drain voltage of M3-2 should be equal to the drain voltage of M3-1. Unfortunately, for real components, all circuit defects or component tolerances typically result in small differences. This offset is compensated for, for example, by this embodiment. For this purpose, semiconductor M3-3 is connected to the drain of M3-2. During the auto-zeroing phase, sw13 is closed, also placing M3-3 in a diode configuration. Therefore, when the drain voltage of M3-2 is higher than the threshold voltage of M3-3 (approximately 0.6 V), current will flow through M3-3, and this current will be proportional to the magnitude of the drain voltage of M3-2.
[0036] Another problem may arise when M3-2 becomes more conductive than M3-1 due to the offset. Then, the drain voltage of M3-2 becomes lower than the threshold voltage of M3-3, and no current flows, making correction impossible. This is why the reference current on the branch of M3-2 is greater than the reference current on the branch of M3-1, so that the compensation circuit is activated independently of the voltage offset. In short, the input differential pair is self-imposed imbalance (by having different bias currents); thus, the compensation circuit can compensate for positive or negative offset voltages. To ensure this imbalance between the two reference currents, a current mirror structure is used, with different dimensions for each branch. Therefore, the output branch of the first stage is slightly over-biased, denoted by the amount ε1. The compensation then works as follows: M3-3 draws a current proportional to the drain voltage of M3-2 (this is a picture of the voltage offset) to bring it back around the threshold voltage of M3-4 (see the IV characteristics of a diode). The first sampling capacitor C... S1 This voltage (drain voltage of M3-2 and M3-3) is used to store the result voltage, which is also the V of M3-3. GS This refers to the voltage that controls the current flowing through M3-3. Therefore, once the comparison phase begins (sw13 is disconnected), the voltage of M3-3... GS Holding from the auto-zero phase allows compensation for offsets sensed during the auto-zero phase, since the current flowing through M3-3 is the same in both phases. Therefore, in C... S1 The ability to store precise voltages can be relevant. The circuit described in the previous paragraphs only details the first stage of this offset-compensated amplifier. In reality, this first stage lacks sufficient gain to function as a comparator. Therefore, a complementary gain stage is added to the output of the first stage. This complementary gain stage is composed of a reference current I...REF This is achieved using the associated amplifier M3-4.
[0037] However, to further improve the accuracy of the circuit, the analog compensation mechanism for the differential input pair moves back and forth on the second gain stage of the amplifier, exhibiting some adaptability. To exhibit "comparator" behavior, M3-4 needs to be in either a blocking state or a pass state. Therefore, in the balanced state, i.e., when sw12 and sw13 are closed and sw11 is open, both inputs are equal, so the output is typically in balance between its two states. Then, the V of M3-4... GS It is close to its threshold voltage (approximately 0.6 V). This is why M3-4 and M3-3 are well matched in the first approximation, and therefore they have equal threshold voltages, because M3-3 makes the first stage output voltage close to its own threshold voltage in a balanced state. However, to further improve accuracy and also to compensate for the voltage offset of M3-4, a compensation circuit is added to the second stage of the amplifier, including M3-5, the second comparator C S2 And switch sw13b. Since this is a single-branch amplification stage, rather than a differential stage including M3-1 and M3-2, the imbalance due to bias current may not occur. Therefore, the size of M3-4 needs to be selected in such a way that it has a threshold voltage slightly larger than that of M3-3, so that M3-4 is turned on rather than blocked in the balanced state. Then, the drain voltage of M3-4 should be higher than the threshold voltage of M3-5 (approximately 0.6 V) during the auto-zeroing phase, so that current can flow through M3-5, thus effectively compensating for the offset of M3-4. Therefore, similar to M3-3 for the first gain stage, M3-5 will make the output voltage U out It approaches its own threshold voltage while having a current flowing through it that is proportional to the voltage offset of M3-4. Then, when the inputs are equal, comparator C S2 The storage allows for a voltage value that reaches a balanced state at the output. Therefore, when entering the comparator phase (SW13A and SW13B are disconnected), another compensation current ε2 is maintained from the auto-zero phase, i.e., ε2 is plugged into the drain of M3-5 and V. out between.
[0038] Summarize the switch states during each phase: In stage #2 ("auto-zeroing" for the sub-circuit of this section): amplifier switches sw12, sw13a and sw13b are closed, while sw11 and sw14 are open. In stage #1 (the “comparison mode” for the sub-circuit of this section): amplifier switches sw11 and sw14 are closed, while sw12, sw13a and sw13b are open.
[0039] Figure 5a A current protection system 100 is schematically shown as an example of a tripping function according to an embodiment. Figure 5a The circuit is based on Figure 1 The circuit. The same reference numerals denote the same... Figure 1 The same or similar parts. Figure 5a In the control unit 200, there are operational amplifiers 220 and latches 225. The latches 225 have input set and reset functions, as well as outputs Q and NQ. Figure 5b describe Figure 5a The timing behavior of the circuit in the diagram is as follows: First, the current protection system 100 is activated at t0. Once the current I reaches t1... Load >I max The comparator subsystem 150 (which will U sh with U ref2 (In comparison) Upon sensing, operational amplifier 220 immediately activates the set input of latch 225, causing a signal change at output NQ almost immediately, i.e., output NQ switches from "1" to "0". Output NQ is connected to the gate of switch M1, thus blocking ("tripping") the current through M1. Note that the timing between t1 and t2 is extended to better see the effect of interest.
[0040] Figure 6a A current protection system 100 is schematically shown, which is an example of implementing a current limiting function according to an embodiment. Figure 6a The circuit is based on Figure 1 The circuit. The same reference numerals denote the same... Figure 1 The same or similar parts. Figure 6a In the control unit 200, a semiconductor 240 and a resistor 245 are configured to set a limit current I. Limit . Figure 6b describe Figure 6a The timing behavior of the circuit in the diagram is as follows: First, the current protection system 100 is activated at t0. Once the current I reaches t1... Load >I Limit The comparator subsystem 150 (which will U sh with U ref1 (As a comparison) if this is sensed, then semiconductor 240 is set or controlled by resistor 245, and the current through M1 decreases at t2. After a settling time, the current through M1 is limited to I at t3. Limit When the overcurrent ends at t4, the voltage at the gate is "restored" to its normal value at t5.
[0041] Figure 7a A current protection system 100 is schematically shown, which is another example of a current limiting function according to an embodiment. Figure 7a The circuit is based on Figure 1 The circuit. The same reference numerals denote the same... Figure 1 The same or similar parts. Figure 7a In this configuration, control unit 200 includes an operational amplifier 260 with hysteresis (e.g., a so-called Schmitt trigger). Operational amplifier 260 controls semiconductor device 265. Resistor 267 is configured to set a limit current I. Limit Another resistor 268 can be placed between the source of semiconductor 265 and output 190. Once the current I at t1... Load >I Limit The comparator subsystem 150 (which will U sh with U ref1 (Through comparison) If the sensor detects this, semiconductor device 265 controls M1 to block the current flowing through M1. At t2, I Load Lower than I again Limit This causes M1 to disconnect again. When the overcurrent still exists, M1 is blocked again, and so on. This continues until the overcurrent (caused by the overcurrent) disappears.
[0042] Figure 8 A flowchart 500 of a method for protecting a load from overcurrent according to an embodiment is shown. In step 502, the first switch M1 (see...) Figure 1 The circuit is closed. The first switch M1 is part of the shunt subsystem 120, which includes the first switch M1 and the shunt resistor 140. The first switch M1 and the shunt resistor 140 are arranged in series. The shunt subsystem 120 is arranged in series with the load 300. In step 504, the shunt voltage U across the shunt resistor 140... sh Sensed. In step 506, the shunt voltage U is shunt using comparator subsystem 150. sh With reference voltage U ref A comparison is performed. The comparator subsystem 150 includes an offset-compensated operational amplifier 160. In step 508, when the shunt voltage U... sh Higher than or equal to the first predetermined reference voltage U ref1 At that time, the current through the first switch M1 is limited.
[0043] Additionally, or by Figure 8 The dashed line depicts, instead of, in step 510, the shunt voltage U across shunt resistor 140 is checked. sh Is it higher than or equal to the second predetermined reference voltage U? ref2 If so, then in step 512, the first switch M1 is opened. Note that the first predetermined reference voltage U... ref1 It can be with U ref2 The same or different voltages.
[0044] On the other hand, some examples are provided.
[0045] Example 1 relates to a current protection system comprising: a shunt subsystem disposed between an input and an output of the current protection system, the shunt subsystem including a first switch and a shunt resistor, the first switch and the shunt resistor being disposed in series; a comparator subsystem disposed in parallel with the shunt resistor, the comparator subsystem being configured to compare a shunt voltage across the shunt resistor with a reference voltage, the comparator subsystem including an offset-compensated operational amplifier; and a control unit disposed between the output of the comparator subsystem and a first control input of the first switch.
[0046] Example 2 relates to the current protection system of Example 1, and further includes a second switch arranged in parallel with the shunt subsystem, wherein a control element is arranged between the output of the comparator subsystem and a second control input of the second switch.
[0047] Example 3 relates to a current protection system of Example 1 or 2, wherein the offset-compensated operational amplifier is designed as an auto-zero operational amplifier system.
[0048] Example 4 relates to a current protection system of Example 1 or 2, wherein the auto-zero operational amplifier is designed as a ping-pong auto-zero operational amplifier system.
[0049] Example 5 relates to a current protection system of Example 1 or 2, wherein the auto-zero operational amplifier includes: a differential pair of semiconductors, wherein the source of a first semiconductor is connected to a reference voltage and its gate and drain are connected to a reference current; the source of a second semiconductor is connected to a shunt voltage via a first phase switch, its gate is connected to the gate of the first semiconductor, and its drain is connected to the reference current; a first amplifier switch is disposed between the shunt voltage and the second semiconductor; a second amplifier switch is disposed between the source of the first semiconductor and the source of the second semiconductor; and a third amplifier switch, the first end of which is connected to the drain of the second semiconductor. A third semiconductor device, the gate of which is connected to the second end of a third amplifier switch; a first capacitor, disposed at the gate of the third semiconductor device; a fourth semiconductor device, the gate of which is connected to the drain of the second semiconductor device and the drain of the third semiconductor device; a fourth amplifier switch, the first end of which is connected to the drain of the fourth semiconductor device; a fifth semiconductor device, the gate of which is connected to the second end of the third amplifier switch; and a second capacitor, disposed at the gate of the fifth semiconductor device; a fifth amplifier switch, the first end of which is connected to the drain of the fourth semiconductor device and the drain of the fifth semiconductor device, and the second end of which is connected to the output of an auto-zero operational amplifier.
[0050] Example 6 relates to a current protection system of any of the preceding examples, wherein the first and second switches are MOSFETs, NMOS, PMOS, bipolar semiconductors, IGBT switches, or relays.
[0051] Example 7 relates to a current protection system of any of the preceding examples, wherein the shunt voltage that can be sensed by the comparator subsystem is less than 1 mV, for example less than 200 μV, for example less than 50 μV.
[0052] Example 8 relates to a current protection system of any of the preceding examples, wherein the control component includes a current-limiting controllable current source configured to be controlled by a semiconductor disposed at the output of a comparator subsystem, thereby limiting the current through the first and second switches when the shunt voltage across the shunt resistor is higher than or equal to a first predetermined reference voltage.
[0053] Example 9 relates to the current protection system of Example 8, wherein the first predetermined reference voltage has hysteresis.
[0054] Example 10 relates to a current protection system of any of Examples 1 to 7, wherein the control component includes a latch whose set input is configured to be set by an operational amplifier such that when the shunt voltage across the shunt resistor is higher than or equal to a second predetermined reference voltage, the inverting output of the latch is configured to block the current through the first switch.
[0055] Example 11 relates to a current protection system of any of Examples 1 to 7, wherein the control element includes a switch disposed between the input and output of the control element, wherein the switch is open when the shunt voltage across the shunt resistor is higher than a second predetermined reference voltage.
[0056] Example 12 relates to a current protection system of any of Examples 1 to 7, wherein the control component consists of wires such that when the shunt voltage across the shunt resistor is higher than a third predetermined reference voltage, the first switch and the second switch are disconnected.
[0057] Example 13 relates to a method for protecting a load from overcurrent, the method comprising the steps of: closing a first switch, the first switch being part of a shunt subsystem including the first switch and a shunt resistor, the first switch being arranged in series with the shunt resistor, the shunt subsystem being arranged in series with the load; sensing a shunt voltage across the shunt resistor; comparing the shunt voltage with a reference voltage by means of a comparator subsystem including an offset-compensated operational amplifier; and limiting the current through the first switch when the shunt voltage is higher than or equal to a first predetermined reference voltage.
[0058] Example 14 relates to the method of Example 13, and further includes the step of: disconnecting the first switch when the shunt voltage across the shunt resistor is higher than or equal to a second predetermined reference voltage.
[0059] Example 15 relates to the method of Example 13 or 14, and further includes the steps of: closing a second switch, the second switch being arranged in parallel with the shunt subsystem; and limiting the current through the second switch when the shunt voltage across the shunt resistor is higher than or equal to a first predetermined reference voltage.
[0060] Example 16 relates to the method of Example 13, 14 or 15, and further includes the step of: disconnecting the second switch when the shunt voltage is higher than or equal to the second predetermined reference voltage.
[0061] Example 17 relates to a system comprising: a current protection system according to any one of claims 1-12; a generator; and at least one load arranged in series with the current protection system and the generator.
[0062] Example 18 relates to the use of a current protection system (100) according to any one of claims 1-12 in an automotive system, particularly for protecting the current protection system itself and / or the vehicle's consumable devices, the motor and / or battery of an electric vehicle, a photovoltaic system and / or its consumable devices.
Claims
1. A current protection system (100), comprising: The shunt subsystem (120) is arranged between the input (110) and the output (190) of the current protection system (100). The shunt subsystem (120) includes a first switch (M1) and a shunt resistor (140), wherein the first switch (M1) and the shunt resistor (140) are arranged in series. The comparator subsystem (150) is arranged in parallel with the shunt resistor (140). The comparator subsystem (150) is configured to convert the shunt voltage (U) across the shunt resistor (140) into a single voltage across the shunt resistor. sh ) and reference voltage (U ref The comparison is performed by the comparator subsystem (150), which includes an offset-compensated operational amplifier (160). as well as The control unit (200) is arranged between the output (180) of the comparator subsystem (150) and the first control input (121) of the first switch (M1).
2. The current protection system (100) according to claim 1 further includes a second switch (M2). The second switch (M2) is arranged in parallel with the shunt subsystem (120), wherein the control unit (200) is arranged between the output (180) of the comparator subsystem (150) and the second control input (122) of the second switch (M2).
3. The current protection system (100) according to claim 1 or 2. The offset-compensated operational amplifier (160) is designed as an automatic zeroing operational amplifier system.
4. The current protection system (100) according to claim 1 or 2. The automatic zeroing operational amplifier (160) is designed as a ping-pong automatic zeroing operational amplifier system.
5. The current protection system (100) according to claim 1 or 2. The automatic zeroing operational amplifier system (160) includes: Differential pairs of semiconductor devices (M3-1, M3-2). The source of the first semiconductor device (M3-1) is connected to the reference voltage (U). ref The gate and drain of the second semiconductor device (M3-2) are connected to a reference current, and the source of the second semiconductor device (M3-2) is connected to the shunt voltage (U) via a first phase switch (sw11). sh The gate is connected to the gate of the first semiconductor device (M3-2), and the drain is connected to the reference current. The first amplifier switch (sw11) is arranged in the shunt voltage (U sh Between the second semiconductor device (M3-2) and the second semiconductor device (M3-2), The second amplifier switch (sw11) is arranged between the source of the first semiconductor device (M3-1) and the source of the second semiconductor device (M3-2); The third amplifier switch (sw13a) has its first end connected to the drain of the second semiconductor device (M3-2); The gate of the third semiconductor device (M3-3) is connected to the second end of the third amplifier switch (sw13a); First capacitor (C) S1 ), is disposed at the gate of the third semiconductor device (M3-3); A fourth semiconductor device (M3-4), the gate of which is connected to the drain of the second semiconductor device (M3-2) and the drain of the third semiconductor device (M3-3); A fourth amplifier switch (sw13b), the first end of which is connected to the drain of the fourth semiconductor device (M3-4); The fifth semiconductor device (M3-5) has its gate connected to the second end of the third amplifier switch (sw13b); as well as Second capacitor (C) S2 ), is disposed at the gate of the fifth semiconductor device (M3-5); A fifth amplifier switch (sw14) has its first end connected to the drain of the fourth semiconductor device (M3-4) and the drain of the fifth semiconductor device (M3-5), and its second end connected to the output (U) of the auto-zero operational amplifier (160). out ).
6. The current protection system (100) according to any one of the preceding claims. The first switch (M1) and the second switch (M2) are MOSFETs, NMOS, PMOS, bipolar semiconductors, IGBT switches, or relays.
7. The current protection system (100) according to any one of the preceding claims. The shunt voltage (U) that can be sensed by the comparator subsystem (150) sh () Less than 1 mV, for example less than 200 μV, for example less than 50 μV.
8. The current protection system (100) according to any one of the preceding claims. The control unit (200) includes a current-limiting controllable current source (245), which is configured to be controlled by a semiconductor device (240) located at the output (180) of the comparator subsystem (150). Therefore, when the shunt voltage (U) across the shunt resistor (140) sh ) is higher than or equal to the first predetermined reference voltage (U) ref1 When the current is limited, the current passing through the first switch (M1) and the second switch (M2) is restricted.
9. The current protection system (100) according to claim 8. Wherein the first predetermined reference voltage (U) ref1 It has a lag.
10. The current protection system (100) according to any one of claims 1-7. The control unit (200) includes a latch (225), the set input of which is configured to be set by an operational amplifier (220). Such that when the shunt voltage (U) across the shunt resistor (140) sh ) is higher than or equal to the second predetermined reference voltage (U) ref2 When the latch (260) is in the reverse output (NQ), the inverted output (NQ) of the latch (260) is configured to block the current passing through the first switch (M1).
11. The current protection system (100) according to any one of claims 1-7. The control unit (200) includes a switch arranged between the input (210) and the output (290) of the control unit (200), wherein when the shunt voltage (U) across the shunt resistor (140) sh ) higher than the second predetermined reference voltage (U ref2 When ), the switch is turned off.
12. The current protection system (100) according to any one of claims 1-7. The control component (200) is composed of wires, such that when the shunt voltage (U) across the shunt resistor (140) is... sh ) higher than the third predetermined reference voltage (U ref3 When the first switch (M1) and the second switch (M2) are open, the second switch is closed.
13. A method for protecting a load (300) from overcurrent, the method comprising the steps of: Close the first switch (M1), which is part of the shunt subsystem (120), which includes the first switch (M1) and the shunt resistor (140), the first switch (M1) and the shunt resistor (140) being arranged in series, and the shunt subsystem (120) being arranged in series with the load (300); Sensing the shunt voltage (U) across the shunt resistor (140) sh ); The shunt voltage (U) is converted by means of the comparator subsystem (150). sh ) and reference voltage (U ref The comparison is performed by the comparator subsystem (150), which includes an offset-compensated operational amplifier (160); and When the shunt voltage (U) sh ) is higher than or equal to the first predetermined reference voltage (U) ref1 When the current is limited, the current through the first switch (M1) is restricted.
14. The method of claim 13, further comprising the step of: When the shunt voltage (U) across the shunt resistor (140) sh ) is higher than or equal to the second predetermined reference voltage (U) ref2 When ), disconnect the first switch (M1).
15. The method of claim 13 or 14, further comprising the step of: Close the second switch (M2), which is arranged in parallel with the shunt subsystem (120); as well as When the shunt voltage (U) across the shunt resistor (140) sh ) is higher than or equal to the first predetermined reference voltage (U) ref1 When the current is limited, the current through the second switch (M2) is restricted.
16. The method according to claim 13, 14 or 15, further comprising the step of: When the shunt voltage (U) sh ) is higher than or equal to the second predetermined reference voltage (U) ref2 When ), disconnect the second switch (M2).
17. A system comprising: A current protection system (100) according to any one of claims 1-12. dynamo; as well as At least one load (300) is arranged in series with the current protection system (100) and the generator.
18. Use of the current protection system (100) according to any one of claims 1-12 in an automotive system, particularly for protecting the current protection system itself and / or the vehicle's consumable devices, the motor and / or battery of an electric vehicle, a photovoltaic system and / or its consumable devices.