A variable resistance resistor

Abstract

The utility model discloses a variable resistance resistance belongs to resistance field, include: fixed resistance unit, switch, switch is connected with fixed resistance unit, control unit is used for controlling the on-off state of switch to change the connection combination of fixed resistance unit through the on-off state of control switch to obtain different total resistance value. The utility model only utilizes the accurate output of a plurality of discrete resistance value of limited number's switch, and allows external resistance demand signal to drive switch array to complete automatic switching directly.

Description

Technical Field

[0001] This utility model belongs to the field of resistors, and in particular relates to a variable resistance resistor. Background Technology

[0002] Currently, in scenarios such as power supply testing, load simulation, and adjustable impedance networks, a resistor with a flexible resistance value is often required. Existing technologies mainly employ the following two types of solutions: One type is the mechanical rotary variable resistor (such as a wire-wound potentiometer or adjustable resistance box), which continuously adjusts the resistance value by rotating the contacts to change the effective length of the resistance wire. However, its disadvantages are that the contacts wear out quickly, have a short lifespan, and cannot withstand large current surges; the resistance adjustment is continuous analog, which cannot quickly and accurately reproduce multiple discrete resistance values; and it lacks a remote control interface, resulting in a low degree of automation.

[0003] Another approach involves combining relay / analog switch arrays with fixed resistors. Relays or semiconductor switches are used to switch multiple fixed resistors in series, parallel, or mixed configurations to obtain different resistance values. The drawbacks are that existing solutions only provide simple series-parallel topologies and lack system optimization for "how to cover the maximum resistance value with the fewest number of switches," resulting in a large number of switches, large size, and high cost. Furthermore, there is a lack of unified upper-level control logic; there is no one-to-one mapping between switching rules and external resistance value requirements, requiring users to manually calculate and control each switch individually, which is inefficient and prone to errors. Finally, a storable, callable, and expandable "resistance configuration scheme library" has not been established, making one-click resistance value switching or remote programmable control impossible. Utility Model Content

[0004] To solve the above technical problems, this utility model provides a variable resistance resistor, comprising: Fixed resistance unit; The switch is connected to the fixed-value resistor unit; The control unit is used to control the on / off state of the switch, and by controlling the on / off state of the switch, to change the connection combination of the fixed resistance unit, thereby obtaining different total resistance values.

[0005] Preferably, the fixed resistance unit includes a first fixed resistor and a second fixed resistor; The first fixed resistor and the second fixed resistor are connected through the switch to form a series or parallel structure.

[0006] Preferably, the switch includes a first switch and a second switch. The first switch is connected between a first fixed resistor and a second fixed resistor, and the second switch is connected across the two ends of the second fixed resistor. By controlling the on / off state of the first switch and the second switch, the connection method of the first fixed resistor and the second fixed resistor can be changed.

[0007] Preferably, the control unit controls the on / off state of the first switch and the second switch according to the externally input resistance demand signal, so as to obtain the total resistance value corresponding to the resistance demand signal.

[0008] Preferably, the fixed resistance unit includes multiple fixed resistors, which are connected through the switch to form multiple different series, parallel, or mixed connection structures.

[0009] Preferably, the switch includes multiple selector switches, each selector switch corresponding to a fixed resistor. By controlling the on / off state of the selector switches, the corresponding fixed resistor can be selectively connected or disconnected, thereby changing the total resistance value.

[0010] Preferably, the control unit controls the on / off state of multiple selector switches according to a preset resistance range to obtain any total resistance value within the range.

[0011] Preferably, the variable resistance resistor further includes an input interface for receiving an externally input resistance requirement signal and transmitting the resistance requirement signal to the control unit.

[0012] Preferably, the control unit includes a memory for storing multiple preset resistance configuration schemes, each resistance configuration scheme corresponding to a combination of switch on / off states.

[0013] Preferably, the control unit selects a resistance configuration scheme that matches the externally input resistance requirement signal from the memory, and controls the on / off state of the switch according to the resistance configuration scheme to obtain the corresponding total resistance value.

[0014] Compared with the prior art, the present invention has the following advantages and technical effects: This invention proposes a variable resistance resistor, which, through an overall architecture of "fixed resistance unit + multiple switch array + control unit", can achieve accurate output of multiple discrete resistance values ​​using only a limited number of switches, and allows external resistance demand signals to directly drive the switch array to complete automatic switching.

[0015] This invention achieves as many target resistance values ​​as possible by reducing the number of switches and using different connection combinations of fixed resistors.

[0016] This invention establishes a deterministic mapping between "resistance requirement - switch on / off state" to achieve one-click resistance setting.

[0017] This utility model also provides a storable and expandable resistance configuration scheme library, so that the same hardware platform can meet the future needs for new resistance values ​​without changing the structure. The variable resistance resistor of this invention is compatible with high current applications, ensuring that the switch and resistor unit maintain reliable contact and stable resistance value after multiple switching operations. Attached Figure Description

[0018] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings: Figure 1 This is a schematic diagram of the system structure of an embodiment of the present utility model. Detailed Implementation

[0019] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0020] It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and although a logical order is shown in the flowchart, in some cases the steps shown or described may be executed in a different order than that shown here.

[0021] like Figure 1 As shown, this embodiment provides a variable resistance resistor, including: Fixed resistance unit; A switch, connected to a fixed-value resistor unit; The control unit is used to control the on / off state of the switch, and by controlling the on / off state of the switch, changes the connection combination of the fixed resistance unit to obtain different total resistance values.

[0022] In this embodiment, the fixed resistance unit can be a single fixed resistor or a modular unit formed by pre-connecting several fixed resistors in series, parallel or mixed connection. Its packaging form can be surface mount, through-hole, copper busbar or three-dimensional stacked busbar to adapt to the current range from milliampere to kiloampere.

[0023] The switch in this embodiment is not limited to any one of mechanical relays, solid-state relays, MOSFETs, IGBTs, thyristors, or MEMS microswitches, nor is its installation position limited—it can be located on one side, both sides, or at the center tap of the resistor unit, or even embedded inside the resistor body to form an integrated "switch-resistor" power module.

[0024] The control unit in this embodiment can be a microcontroller, DSP, FPGA, CPLD, ARM core SoC, RISC-V core MCU, or a pure hardware state machine or analog comparator array; its output stage can directly drive the switching coil, or it can achieve potential isolation and power amplification through optocouplers, magnetic couplers, digital isolators, gate drivers or current-type drive chips.

[0025] The signal link between the control unit and the switch can be a parallel bus, a serial bus (SPI / I²C / UART), a differential bus (RS-485 / CAN / LVDS), or a wireless link (Bluetooth, ZigBee, Sub-1G, UWB, Wi-Fi). In applications with stringent electromagnetic compatibility requirements, fiber optic or plastic fiber optic cables can be used to achieve a "metalless" interface. The mathematical essence of the connection combination is the "edge-switching" problem in graph theory of resistor networks: considering fixed-value resistor units as edges of the graph and switches as on / off control variables on the edges, the total resistance value is the equivalent resistance between any two ports of the graph; this equivalent resistance changes with the switch state vector, forming a discrete but definite resistance space. This resistance space can be a one-dimensional monotonic sequence, a two-dimensional or higher-dimensional matrix, or even extended to a "resistance-temperature" or "resistance-voltage" two-parameter space through nonlinear resistors (such as NTC, PTC, VDR).

[0026] The control unit can run graph theory algorithms, matrix inversion, LU decomposition, Jacobi iteration or deep learning inference to calculate the equivalent resistance corresponding to any switch state vector in real time; it can also use the "lookup table + interpolation" method to solidify the pre-calculated switch state vector table in non-volatile memory to achieve microsecond-level switching.

[0027] Furthermore, the fixed resistance unit includes a first fixed resistor and a second fixed resistor; The first fixed resistor and the second fixed resistor are connected by a switch to form a series or parallel structure.

[0028] Furthermore, in this embodiment, the first fixed resistor and the second fixed resistor can have the same nominal resistance value, or they can be in a binary weighted relationship (such as R and 2R), or in a decimal weighted relationship (such as 1Ω, 10Ω, 100Ω), or they can be distributed according to precision series such as E96, E192, so as to obtain a logarithmically uniform or linearly uniform step resolution in the total resistance value space.

[0029] The minimum number of switches can be reduced to two: one for series / parallel mode switching and the other for short-circuit / open-circuit redundancy; it can also be expanded to four to achieve four topologies: series, parallel, single first resistor, and single second resistor.

[0030] If the two resistors have different power ratings, their power nodes and signal nodes can be separated by a switch to achieve a heterogeneous design of "small power precision adjustment + large power redundant bypass".

[0031] The resistor body can be made of metal foil, metal film, metal oxide, wire winding, thick film, thin film, silicon-based integrated resistor, copper-nickel-manganese alloy foil, constantan foil, manganese-copper foil, nickel-chromium foil or iron-chromium-aluminum foil, to achieve a compromise between indicators such as temperature drift, power density, thermoelectric potential, noise, and long-term stability.

[0032] As a preferred implementation method, the resistor in this embodiment is a high-power ceramic tube resistor with no inductance or low inductance.

[0033] In a series configuration, the total resistance RS = R1 + R2; in a parallel configuration, the total resistance RP = R1·R2 / (R1 + R2). When R1 = R2 = R, RS = 2R and RP = 0.5R, forming a 4:1 resistance ratio. If R1 and R2 are in a 10:1 ratio, then RS ≈ 11R2 and RP ≈ 0.909R2, expanding the ratio to 12.1:1. Only two resistors are needed to cover a tenth octave band. The switch needs to handle the full current in series mode and only the branch current in parallel mode. Therefore, this embodiment allows for differentiated selection of switch current ratings, reducing costs. If the two resistors are placed on different heat sinks, the heat conduction path can be switched via the switch, enabling programmable "resistance-thermal resistance" dual parameters and further expanding the system's capabilities.

[0034] Furthermore, the switch includes a first switch and a second switch. The first switch is connected between a first fixed resistor and a second fixed resistor, and the second switch is connected across the two ends of the second fixed resistor. By controlling the on / off state of the first switch and the second switch, the connection method of the first fixed resistor and the second fixed resistor is changed.

[0035] Further, the combinational logic of the first switch and the second switch in this embodiment can construct seven states: "pure series, pure parallel, only R1 connected, only R2 connected, R1 short-circuited, R2 short-circuited, both resistors open-circuited", forming a 3-bit virtual state machine. If a normally open relay is used, the default state is "both resistors open-circuited", which is suitable for high-safety occasions; if a normally closed relay is used, the default state is "pure series", which is suitable for fail-safe low-resistance freewheeling occasions. The first switch is in the "on" state in the series mode, and its contact resistance will be superimposed into the total resistance. Therefore, the "four-wire Kelvin" connection can be adopted for this switch to eliminate the error introduced by the contact resistance; the second switch is in the "short-circuit" state in the parallel mode, and its on-resistance is parallel with R2. If the on-resistance << R2, the equivalent resistance error can be ignored. If both switches are solid-state MOSFETs, their on-resistance RDS(on) has a positive temperature coefficient, which can compensate for the positive temperature coefficient of the copper base of R1 and R2, realizing the self-stabilization of "total resistance versus temperature".

[0036] The control unit can perform soft-start on the first switch by means of PWM to suppress voltage spikes caused by series inductance; it can also drive the second switch through synchronous rectification to realize "zero-current turn-off" and reduce the risk of parallel arcing.

[0037] Further, the control unit controls the on-off states of the first switch and the second switch according to the externally input resistance demand signal to obtain a total resistance value corresponding to the resistance demand signal.

[0038] Further, the external resistance demand signal in this embodiment can be 0-10V analog voltage, 4-20mA current loop, 0-5kΩ resistance modulation, PWM duty cycle, frequency modulation, single-wire digital signal (such as DHT11 protocol), RS-232 frame, CAN frame, Ethernet UDP packet, or wireless LoRa frame; Inside the control unit, the above signals are quantified into discrete digital codes by means of ADC, current loop sampling, capacitance-frequency conversion, STM32 input capture, FPGA TDC or SDR demodulation. The mapping relationship between the digital codes and the "switch state vector" can be stored in a look-up table LUT, EEPROM, Flash, FRAM, MRAM, RRAM or on-chip fuse array; it can also be calculated in real time by a runtime algorithm to save storage space. If the demand signal exceeds the synthesizable resistance range, the control unit can perform "nearest neighbor rounding", "linear interpolation", "triangular wave jitter + average" or Σ-Δ modulation to approximate the target resistance in the time domain and realize "virtual continuous adjustment".

[0039] Further, the fixed resistance unit comprises a plurality of fixed resistors, and the plurality of fixed resistors are connected through switches to form a plurality of different series, parallel or series-parallel structures.

[0040] Furthermore, this embodiment can expand the fixed resistance unit from two resistors to three or more, thus entering the category of "network integration". Multiple fixed resistors can be arranged into a linear array, a two-dimensional matrix, a three-dimensional stack, a ring, a sector, a honeycomb, a Hilbert curve, or a random graph topology; the switches are correspondingly arranged at nodes, branches, bridging, diagonals, redundant bypasses, or virtual neutral points.

[0041] Taking three resistors as an example, 2^6 = 64 states can be achieved using six single-pole single-throw switches, but only about 20 of these produce unique resistance values. Through graph theory simplification, 12 "valid states" can be selected, covering the range of 0.2R to 3.3R, with a step resolution of 0.1R. If binary weighting (R, 2R, 4R) is used, the total resistance value space exhibits a 3-bit digital-to-analog conversion characteristic, allowing for eight resistance value outputs to be achieved using three selector switches, simplifying the driving process.

[0042] Power distribution among multiple resistors can be achieved through a "circulating current cancellation" layout: magnetic fluxes in adjacent current directions cancel each other out, reducing parasitic inductance; alternatively, "orthogonal stacking" can be used to make high-frequency magnetic fields perpendicular to each other, reducing mutual inductance. The PCB routing of the switch array can adopt a "Kelvin-six-wire" structure: two wires carry current, two for sampling voltage, and two for driving the coil, achieving full isolation. For high-voltage applications, resistors can be etched segmentally onto the ceramic substrate to form a "voltage divider chain" with a withstand voltage of 5kV or higher; switches use vacuum relays or SiCJFETs stacked in series to ensure off-state withstand voltage. To achieve "negative resistance" or "exceeding boundary resistance," the network and an external amplifier can be combined to form an active impedance transformer; however, this is still limited to a passive network, so a forward resistance of 0.05R~10kΩ is achieved only through series and parallel connections.

[0043] Furthermore, the switch includes multiple selector switches, each corresponding to a fixed resistor. By controlling the on / off state of the selector switches, the corresponding fixed resistor can be selectively connected or disconnected, thereby changing the total resistance value.

[0044] Furthermore, the selector switch in this embodiment can employ either a one-to-one exclusive mapping or a one-to-many coded mapping. Under exclusive mapping, N resistors require N switches, simplifying the hardware, but only N+1 possible resistance combinations (including all open). Under coded mapping, log2N bits of binary code can select 2^log2N = N resistors, significantly reducing drive lines. The selector switch can be placed at one end of a resistor (lower-end switching) or at both ends (double-end switching), the latter allowing the "open" state to float completely, preventing leakage current. For precision applications, a high-resistance MOSFET can be connected in parallel with the selector switch for "soft discharge," preventing electrostatic discharge caused by open-circuit charge accumulation. The selector switch's drive stage can employ a "shift register + push-pull" chain structure, requiring only 2 lines (CLK / DATA) for unlimited cascading, suitable for large arrays of hundreds of resistors. The register output can be latched to prevent erroneous switch operation when the MCU crashes. Feedback diagnosis of the selector switch can be achieved through the "readback" pin: the driver stage connects a 1Ω sampling resistor in series with the switch coil or gate, uses an ADC to detect the current waveform, and determines whether the contacts are stuck or the MOSFET is broken down, thus achieving self-diagnosis.

[0045] Furthermore, the control unit controls the on / off state of multiple selector switches according to a preset resistance range to obtain any total resistance value within the resistance range.

[0046] Furthermore, the preset resistance range in this embodiment can be stored in a multi-dimensional array: one dimension is the lower limit of the resistance, two dimensions are the upper limit, three dimensions are the allowable step size, and four dimensions are the temperature coefficient compensation value. After the control unit is powered on, it first reads the temperature sensor and dynamically adjusts the upper and lower limits according to the temperature coefficient to prevent the resistance value from drifting out of the range at high temperatures. If the required resistance value falls between two synthesizable resistance values, the control unit can perform a "time-resistance" dual-point alternation: switching between the two resistance values ​​with a 50% duty cycle, and achieving an equivalent intermediate resistance value through external RC averaging or digital post-filtering; with a duty cycle resolution of 12 bits, the theoretical accuracy can reach 0.025%. For scenarios requiring monotonically increasing values, the control unit can run a "sorting-deduplication-interpolation" algorithm: first enumerate all switch states, calculate the equivalent resistance value, sort and generate a monotonically increasing LUT, then delete duplicate values, and finally insert the nearest neighbor at the gap to ensure that the resistance value sequence is monotonically non-falling back.

[0047] Furthermore, the variable resistance resistor also includes an input interface, which is used to receive an external resistance demand signal and transmit the resistance demand signal to the control unit.

[0048] Furthermore, the input interface can be physically morphologically represented as: 3.5mm audio jack (0-2V analog); RJ45 (Ethernet PoE, UDP broadcast); USB Type-C (PD protocol, virtual serial port); Coaxial BNC (0-10V differential); Fiber optic ST connector (IEC60870-5-104 protocol). Spring-loaded crimp terminal (4-20mA).

[0049] The interface circuit must have surge, EFT, ESD, lightning protection, reverse connection protection, and 24V misconnection protection. For the 4-20mA ring, it must first be converted to 0.6-3V via a 150Ω precision sampling resistor, and then amplified to the ADC full scale by an instrumentation amplifier; the sampling resistor temperature drift should be ≤5ppm / °C to ensure 0.1% accuracy. For the wireless interface, the LoRa 433MHz band can be used, with a line-of-sight range of 3km in urban areas and a data rate of 62.5kbps. The protocol stack has built-in AES-128 encryption to prevent unauthorized writes to the resistor value. The interface firmware supports OTA upgrades, retains dual-zone boot, and automatically rolls back upon upgrade failure.

[0050] Furthermore, the control unit includes a memory for storing multiple preset resistance configuration schemes, each resistance configuration scheme corresponding to a combination of switch on / off states.

[0051] Furthermore, the memory types cover: On-chip Flash (10,000 erase / write cycles, suitable for hardening); External EEPROM (1 million erase / write cycles, suitable for frequent updates); FRAM (10^13 erase / write cycles, suitable for high-speed logging); uSD card (GB level, suitable for on-site capacity expansion); NFC tag (passive, suitable for factory defaults).

[0052] Each configuration scheme can be structured as follows: Header byte 0x55 (magic number); 2-byte CRC16 (checksum); 4-byte timestamp (Unix time); 1-byte temperature compensation index; N-byte switch status bitmap (each bit corresponds to one switch); 4-byte equivalent resistance (IEEE 754 single precision); 16-byte user comment (ASCII).

[0053] The memory supports wear leveling: the EEPROM has 256B physical sectors, 252B logical sectors, and the remaining 4B records the erase / write count. After 500,000 erase / write cycles, it automatically migrates to a new sector. The scheme library can be exported as a CSV file via host computer software for easy editing in Excel and then rewriting.

[0054] Furthermore, the control unit selects a resistance configuration scheme that matches the resistance requirement signal from the memory based on the externally input resistance requirement signal, and controls the on / off state of the switch according to the resistance configuration scheme to obtain the corresponding total resistance value.

[0055] Furthermore, the matching described in this embodiment employs nearest neighbor rounding, linear interpolation, spline interpolation, or machine learning regression. For the nearest neighbor algorithm, the control unit performs a binary search with a time complexity of O(logM), where M is the number of solutions. If M=1024, the search requires only 10 comparisons, taking less than 20µs. If a tolerance field (±0.5%) is required for the signal, the control unit first filters out all solutions falling within the tolerance band, then sorts them according to the principle of "least number of switching actions," avoiding unnecessary relay jitter and extending their lifespan.

[0056] The switching process employs a "close first, disconnect later" strategy: first close the newly added switch in the target state, then disconnect the redundant switch to ensure that no instantaneous open-circuit high voltage occurs during the intermediate process.

[0057] After the switch is completed, the control unit reads back the actual resistance value (via four-wire sampling) and compares it with the target value. If the deviation is >0.05%, the "micro-motion correction" subroutine is triggered. By performing 8-bit gate voltage fine-tuning on the solid-state MOSFET and utilizing the change in its linear region resistance, a fine adjustment of ±1Ω can be achieved, ultimately resulting in a closed-loop accuracy of 0.01%.

[0058] The above are merely preferred embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A variable resistance resistor, characterized in that, include: Fixed resistance unit; The switch is connected to the fixed-value resistor unit; The control unit is used to control the on / off state of the switch, and by controlling the on / off state of the switch, to change the connection combination of the fixed resistance unit, thereby obtaining different total resistance values. An input interface is provided for receiving an externally input resistance requirement signal and transmitting the resistance requirement signal to the control unit. The fixed resistance unit includes a first fixed resistor and a second fixed resistor; the first fixed resistor and the second fixed resistor are connected through the switch to form a series or parallel structure. The switch includes a first switch and a second switch. The first switch is connected between a first fixed resistor and a second fixed resistor, and the second switch is connected across the two ends of the second fixed resistor. By controlling the on / off state of the first switch and the second switch, the connection method of the first fixed resistor and the second fixed resistor can be changed. The control unit controls the on / off state of the first switch and the second switch according to the externally input resistance demand signal, so as to obtain the total resistance value corresponding to the resistance demand signal. The control unit includes a memory for storing multiple preset resistance configuration schemes, each resistance configuration scheme corresponding to a switch on / off state combination; the control unit selects a resistance configuration scheme that matches the resistance requirement signal from the memory according to the externally input resistance requirement signal, and controls the on / off state of the switch according to the resistance configuration scheme to obtain the corresponding total resistance value.

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