Current acquisition circuit of solid-state power controller and current temperature compensation method thereof

Abstract

The present invention relates to the field of power distribution system control technology, and specifically to a current acquisition circuit of a solid-state power controller and a current temperature compensation method thereof. A current acquisition circuit includes a power switch module, which includes a switch input end and a switch output end; a current acquisition module is connected to the power switch module, and the other end of the current acquisition module is connected to an MCU; a switch drive module, one end of which is connected to the power switch module, and the other end of the switch drive module is connected to an MCU; a temperature acquisition module, which is connected to an MCU; and a communication module, which is connected to an MCU. The dual-power drive method of the solid-state power controller provided by the present invention reduces the switching loss when the MOS tube is turned off, reduces the duration of the possible Miller oscillation, and prevents the tube from burning. The present invention also provides a current temperature compensation method, which solves the problem of device temperature drift and quantization reference error generated when the temperature changes, thereby causing the output current to deviate.

Description

Technical Field

[0001] The present invention relates to the technical field of power distribution system control, and in particular to a current acquisition circuit of a solid-state power controller and a current temperature compensation method thereof. Background Art

[0002] As the aerospace industry develops towards multi-electrification and full electrification, the number of electrical equipment is increasing, and the power of the whole machine is also increasing, which puts forward new and higher requirements on the performance and reliability of the power distribution system. However, the traditional electromechanical power distribution system has slow fault response and low automation and intelligence. In this context, with the development of power semiconductor devices, solid-state power distribution technology based on MOSFET, IGBT, etc. has emerged.

[0003] The core technology of solid-state power distribution is solid-state power control technology, and the solid-state power controller component (SSPC) developed with this technology is a high-performance, high-reliability solid-state switch. Traditional fuses are irreversible and cannot work after burning out, while SSPC controls the opening and closing of the switch tube through the drive circuit, which is recoverable; secondly, the relay and Hall current sensor are both large in size, while SSPC can be made relatively small; in addition, SSPC does not require additional auxiliary power supply. Due to its contactless and no switch life limit, high safety, high reliability, and flexible configuration, SSPC is very suitable for use in power distribution systems with high reliability requirements such as aerospace, ships, and vehicle-mounted tanks and military industries.

[0004] However, due to the temperature drift characteristics of the device, some circuit parameters change, such as ADC quantization reference, resistance value of resistive devices, reference voltage, etc. This change will cause the output parameters and acquisition parameters to deviate from the expected values ​​to a certain extent, reducing the reliability of the controller. In severe cases, it will cause the controller to malfunction or not operate, causing safety accidents. Different devices are affected by temperature changes to different degrees, and the interaction between devices makes it difficult to implement a specific compensation method based on a specific device. If handled improperly, it will not only slow down the response speed and increase the amount of calculation, but may also introduce new sources of error.

[0005] In common MOS tube drive circuits, the reference ground level of the power input is 0 V. Under this level standard, when the MOS FET state is switched, the discharge of the energy storage device in the circuit and the changing magnetic field in the circuit will reduce the level change speed of the edge, increasing the time that the MOSFET works in the linear region; if Miller oscillation exists at the edge at the same time, the MOSFET will work in the linear region for a short time, resulting in higher switching losses. Working in the linear region for a long time will have a great impact on the life of the tube and pose a hidden danger to the stability of the SSPC.

[0006] In order to solve the above problems, the present invention provides a current acquisition circuit of a solid-state power controller and a current temperature compensation method thereof, as well as a dual power supply method for improving the shutdown efficiency of MOS tubes and reducing switching losses. Summary of the invention

[0007] An object of the present invention is to solve at least the above problems and / or disadvantages and to provide at least the advantages which will be described hereinafter.

[0008] Another object of the present invention is to provide a current collection circuit for a solid-state power controller, which reduces Miller oscillation during shutdown and prevents tube burning.

[0009] Another object of the present invention is to provide a current temperature compensation method for a current acquisition circuit of a solid-state power controller, which solves the problem of device temperature drift and quantization reference error caused by temperature changes, which in turn lead to output current deviation.

[0010] In order to achieve these purposes and other advantages according to the present invention, the present invention provides a current acquisition circuit of a solid-state power controller, comprising:

[0011] A power switch module, comprising a switch input terminal and a switch output terminal;

[0012] A current acquisition module, one end of which is located between the switch input end and the switch output end and connected to the power switch module, and the other end of the current acquisition module is connected to the MCU;

[0013] A switch driving module, one end of which is connected to the power switch module, and the other end of the switch driving module is connected to the MCU;

[0014] A temperature acquisition module connected to the MCU;

[0015] A communication module is connected to the MCU.

[0016] Preferably, the power switch module includes a power switch MOS tube, the drain of the power switch MOS tube is the switch input end, the source of the power switch MOS tube is connected to one end of the current acquisition module and serves as the switch output end, and the gate of the power switch MOS tube is connected to the output end of the switch driving module.

[0017] Preferably, it is characterized in that the switch driving module comprises a MOS driving chip, the output end of the MOS driving chip is connected to the power switch module, and the input end of the MOS driving chip is connected to the MCU;

[0018] Wherein, the MOS driver chip is powered by +15V and -15V.

[0019] Preferably, the current acquisition circuit includes a sampling resistor and a differential amplifier, the input end of the sampling resistor is connected between the switch input end and the switch output end, the output end of the sampling resistor is connected to one end of the differential amplifier, and the other end of the differential amplifier is connected to the MCU; an analog-to-digital converter is provided in the MCU, and the analog-to-digital converter is connected to the other end of the differential amplifier.

[0020] The temperature acquisition module includes a temperature sensor, which is connected to an analog-to-digital converter in the MCU. The analog-to-digital converter is used to quantify the voltage value of the temperature sensor and the sampling resistor.

[0021] The present invention also provides a current temperature compensation method for a current acquisition circuit of a solid-state power controller, comprising:

[0022] Set the compensation zero point, and use the resistance value of the sampling resistor under the compensation zero point as the standard value;

[0023] Calculating the ratio of the resistance value of the sampling resistor at the real-time temperature to the standard value, and defining the ratio as a compensation coefficient of the output current;

[0024] The compensation current at the real-time temperature is obtained by combining the output current value of the sampling resistor at the real-time temperature, the compensation coefficient, and the quantized voltage value of the sampling resistor through the temperature acquisition module;

[0025] Preferably, the temperature acquisition module is also compensated and zeroed:

[0026] At the compensation zero point, the voltage value corresponding to the temperature acquisition module is quantized after being sampled by an analog-to-digital converter provided in the MCU to obtain a compensation base;

[0027] At real-time temperature, the voltage value corresponding to the temperature acquisition module is quantized after being sampled by an analog-to-digital converter set in the MCU to obtain a real-time temperature quantization value;

[0028] The compensation coefficient is optimized by combining the compensation base and the real-time temperature quantization value to obtain a final compensation coefficient.

[0029] Preferably, the ratio of the resistance value of the sampling resistor at the real-time temperature to the standard value is calculated, and the ratio is defined as the compensation coefficient of the output current. The theoretical basis of the algorithm implementation is summarized as follows, specifically including:

[0030] At the real-time temperature T, the resistance of the sampling resistor is R X for

[0031] R X =R 25-[(T-25℃)*R_ppm*R 25 ] (1)

[0032] According to the ratio of the resistance value of the sampling resistor to the standard value, the compensation coefficient K of the output current is obtained.

[0033] K=R X / R 25 (2)

[0034] According to (1) and (2), the output current compensation coefficient K can be obtained.

[0035] K=1-((T-25℃)*R_ppm) (3)

[0036] Among them, the normal temperature (25℃) is set as the compensation zero point, R_ppm is the temperature drift coefficient of the sampling resistor, R 25 To compensate the resistance value of the sampling resistor under zero point.

[0037] Preferably, the compensation current at the real-time temperature is obtained by combining the output current value of the sampling resistor at the real-time temperature, the compensation coefficient, and the quantized voltage value of the sampling resistor through the temperature acquisition module, including:

[0038] At the real-time temperature T, the voltage difference across the sampling resistor is sampled to obtain ΔV x According to Ohm's law, the compensated current value I D

[0039] I D =ΔV X / R X (4)

[0040] Substituting formula (2) into formula (4), we can obtain:

[0041] I D =ΔV X / (R 25 *K) (5)

[0042] ΔV x After being amplified by the differential amplifier, it becomes ΔV x *α, and then sampled by the analog-to-digital converter set in the MCU to obtain the quantized value N X , and the difference ΔV across the sampling resistor can be obtained by inverse quantization. x

[0043] ΔV X =N X *U m / [(2 n -1)*α] (6)

[0044] Substituting (6) into (5), the output current after compensation is I D

[0045] I D = {N X *U m / [(2 n -1)*α]} / ((R 25 *K)) (7)

[0046] The product term {Um / [(2 n -1)*α*R 25 ) is the current sampling resolution. By taking this part out, we can get

[0047]

[0048] Among them, let the effective number of bits of the analog-to-digital converter be n, and Um be the maximum range 2 n -1, and α is the closed-loop gain of the differential amplifier.

[0049] Preferably, it also includes setting of compensation zero point of temperature acquisition module:

[0050] When setting the compensation zero point, the voltage value corresponding to the temperature acquisition module is V Z , the compensation base after sampling by the MCU's analog-to-digital converter is T Z , which is stored in the MCU after manual measurement at 25°C.

[0051] At real-time temperature, the real-time temperature quantization value sampled by MCU is Tx, and the temperature characteristic voltage value V input to MCU X It can be obtained by inverse quantization calculation:

[0052] V X =U m *T X / (2 n -1) (9)

[0053] The voltage and temperature change relationship of the temperature acquisition module used is linearly positively correlated. The proportional coefficient of temperature T and voltage V is set to β. According to formula (9), we get

[0054] T=β*V X (10)

[0055] Substituting Vx in equation (10) into equation (9), we get the real-time temperature T

[0056] T=β*U m *T X / (2 n -1) (11)

[0057] T in formula (11) X Available T X -T Z replace:

[0058] T-25℃=β*U m *(T X -T Z ) / (2 n -1) (12)

[0059] Substituting (12) into (3), we get the compensation coefficient K1 in the current:

[0060] K1=1-[β*U m *(T X -T Z ) / (2 n -1)]*R_ppm (13)

[0061] Preferably, substitute formula (10) into formula (8) to obtain the compensation current I D

[0062]

[0063] Since the MCU does not support floating-point operations, R_ppm is replaced by R_k, so that R_k = 1 / R_ppm, and the compensation current I is obtained. D for

[0064]

[0065] The present invention has at least the following beneficial effects:

[0066] 1. The current acquisition circuit of the solid-state power controller provided by the present invention realizes the rapid shutdown of the power MOSFET and reduces the loss and risk caused by Miller oscillation.

[0067] 2. The current acquisition circuit of the solid-state power controller provided by the present invention has a simple structure, low cost, market competitiveness, and is easy to promote.

[0068] 3. The current acquisition circuit of the solid-state power controller provided by the present invention greatly reduces the impact of product consistency caused by individual differences in components.

[0069] 4. The current temperature compensation method of the current acquisition circuit of the solid-state power controller provided by the present invention does not investigate the source of the output error caused by the existing temperature change, so that the algorithm has a wider range of applications, the algorithm model is suitable for most temperature compensation scenarios, and the implementation is simple. BRIEF DESCRIPTION OF THE DRAWINGS

[0070] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0071] Figure 1 It is a circuit schematic diagram of the current acquisition circuit of the solid-state power controller described in the present invention;

[0072] Figure 2 It is a circuit schematic diagram of an embodiment of a current acquisition circuit of a solid-state power controller according to the present invention;

[0073] Figure 3 The U of the MOSFET when the MOSFET driver module uses 0V as the reference ground GS Waveform graph;

[0074] Figure 4 When the MOSFET driver module uses -15V as the reference ground, the MOSFET U GS Waveform graph;

[0075] Figure 5 The present invention is a flow chart of a current temperature compensation method for a current acquisition circuit of a solid-state power controller. DETAILED DESCRIPTION

[0076] The present invention is further described in detail below in conjunction with the accompanying drawings so that those skilled in the art can implement the invention with reference to the description.

[0077] In this specification, when an element is referred to as being “connected or coupled to” another element or “disposed in” another element, it may be “directly” connected or coupled to another element or “directly” disposed in another element. Or connected or coupled to another element or disposed in another element in a manner that other elements are interposed therebetween, unless it is described as being “directly coupled or connected to” another element or “directly disposed” in another element. In addition, it should be understood that when an element is referred to as being “on another element,” “above another element,” “under another element,” or “under another element,” it may be “directly” in contact with another element or in contact with another element in a manner that other elements are interposed therebetween, unless it is described as being in direct contact with another element.

[0078] The present invention provides a current temperature compensation method for a current acquisition circuit of a solid-state power controller, such as Figure 5 As shown, including:

[0079] Step 001, setting the compensation zero point, and taking the resistance value of the sampling resistor at the compensation zero point as the standard value;

[0080] Step 002, calculating the ratio of the resistance value of the sampling resistor at the real-time temperature to the standard value, and defining the ratio as a compensation coefficient of the output current;

[0081] Step 003, obtaining a compensation current at the real-time temperature by combining the output current value of the sampling resistor at the real-time temperature, the compensation coefficient, and the quantized voltage value of the sampling resistor through a temperature acquisition module;

[0082] The sampling resistor and the compensation circuit are the sampling resistor and the compensation circuit in the current acquisition circuit of the solid-state power controller mentioned above.

[0083] Since the temperature drift characteristics of the resistor are relatively stable, the change of its resistance value can accurately reflect the change of temperature, and the two are in a linear relationship. At the same time, when the output voltage is constant, the output current is inversely proportional to the resistance value of the resistive load. By setting the compensation zero point, the resistance value at the compensation zero point temperature is used as the standard value. When the temperature changes, the compensation coefficient of the output current can be obtained by calculating the ratio of the resistance value at the current temperature to the standard value, thereby improving the overall stability of the output part.

[0084] Based on the above situation, specifically, before step 003, the method further includes: compensating and adjusting the zero point of the temperature sensor:

[0085] At the compensation zero point, the voltage value corresponding to the temperature sensor is quantized after being sampled by an analog-to-digital converter provided in the MCU to obtain a compensation base;

[0086] At real-time temperature, the voltage value corresponding to the temperature sensor is quantized after being sampled by an analog-to-digital converter set in the MCU to obtain a real-time temperature quantization value;

[0087] The compensation coefficient is optimized by combining the compensation base and the real-time temperature quantization value to obtain a final compensation coefficient.

[0088] Based on the above situation, in another embodiment, the calculation of the ratio of the resistance value of the sampling resistor at the real-time temperature to the standard value and defining the ratio as the compensation coefficient of the output current includes:

[0089] More specifically, let room temperature (25°C) be the temperature compensation zero point. At this temperature, the resistance of the sampling resistor R is R 25 , the voltage difference across the sampling resistor R is ΔV 25 , the magnification is α, and the output current I 25 As the standard current value.

[0090] Assume that the number of effective bits of the ADC is n,2 n -1 corresponds to the maximum range voltage value Um. ΔV 25 After being amplified by the differential amplifier, the digital quantity quantized by the ADC is set as N 25 , then

[0091] N 25 =(ΔV 25 *α / U m )(2 n -1) (00)

[0092] The current value at 25°C is

[0093] I 25 =N 25 *U m / (R 25 *α*(2 n -1)) (01)

[0094] Under the influence of temperature drift characteristics, the resistance value Rx of the sampling resistor becomes

[0095] R X =R 25 -[(T-25℃)*R_ppm*R 25 ] (1)

[0096] According to the ratio of the resistance value of the sampling resistor to the standard value, the compensation coefficient K of the output current is obtained.

[0097] K=R X / R 25 (2)

[0098] According to (1) and (2), the output current compensation coefficient K can be obtained.

[0099] K=1-((T-25℃)*R_ppm) (3)

[0100] Among them, the normal temperature (25°C) is set as the compensation zero point, R_ppm is the temperature drift coefficient of the sampling resistor (unit: R_ppmR_ppmm / °C), and its resistance is negatively correlated with the temperature.

[0101] On the basis of the above embodiment, specifically, the temperature acquisition module combines the output current value of the sampling resistor at the real-time temperature, the compensation coefficient, and the quantized voltage value of the sampling resistor to obtain the compensation current at the real-time temperature, including:

[0102] At the real-time temperature T, the voltage difference across the sampling resistor is sampled to obtain ΔV x According to Ohm's law, the compensated current value I D

[0103] I D =ΔV X / R X (4)

[0104] Substituting formula (2) into formula (4), we can obtain:

[0105] I D =ΔV X / (R 25 *K) (5)

[0106] ΔV x After being amplified by the differential amplifier, it becomes ΔV x *α, and then sampled by the analog-to-digital converter set in the MCU to obtain the quantized value N X , and the difference ΔV across the sampling resistor can be obtained by inverse quantization. x

[0107] ΔV X =N X *U m / [(2 n -1)*α] (6)

[0108] Substituting (6) into (5), the output current after compensation is I D

[0109] I D = {N X *U m / [(2 n -1)*α]} / ((R 25 *K)) (7)

[0110] The product term {Um / [(2 n -1)*α*R 25 ) is the current sampling resolution. By taking this part out, we can get

[0111]

[0112] Among them, let the effective number of bits of the analog-to-digital converter be n, and Um be the maximum range 2 n -1, and α is the closed-loop gain of the differential amplifier.

[0113] According to formula (00), formula (4), and formula (2), the current compensation coefficient can also be obtained as

[0114] K=R X / R 25 =N X / N 25

[0115] Then the compensation current at the current temperature can also be expressed as

[0116] I D =I X (N X )*K≈I 25 (N 25 )

[0117] Specifically, it also includes compensating and adjusting the zero point of the temperature sensor:

[0118] The temperature is calibrated by a high-precision analog IC temperature sensor LM60CIM3, which converts temperature information into voltage information and quantizes it through ADC, recorded as T () .

[0119] The voltage change of this temperature sensor is positively correlated with the ambient temperature. The voltage is greater than zero in the range of -40℃ to 125℃: the corresponding voltage value at -40℃ is 174mV, and the corresponding voltage at 125℃ is 1205mV.

[0120] The following describes the software zeroing method for the temperature zero point of the LM60CIM3:

[0121] When the temperature is adjusted to zero at 25°C, the voltage value corresponding to the temperature sensor is V Z , the compensation base after sampling by the analog-to-digital converter set in the MCU is T Z , which is stored in the MCU after manual measurement at 25°C.

[0122] At real-time temperature, the real-time temperature quantization value sampled by MCU is Tx, and the temperature characteristic voltage value V input to MCU X It can be obtained by inverse quantization calculation:

[0123] V X =U m *T X / (2 n -1) (9)

[0124] The voltage and temperature change relationship of the temperature acquisition module used is linearly positively correlated. The proportional coefficient of temperature T and voltage V is set to β. According to formula (9), we get

[0125] T=β*V X (10)

[0126] Substituting Vx in equation (10) into equation (9), we get the real-time temperature T

[0127] T=β*U m *T X / (2 n -1) (11)

[0128] T in formula (11) X Available T X -T Z replace:

[0129] T-25℃=β*U m *(T X -T Z ) / (2 n -1) (12)

[0130] Substituting (12) into (3), we get the compensation coefficient K1 in the current:

[0131] K1=1-[β*U m *(T X -T Z ) / (2 n -1)]*R_ppm (13)

[0132] Formula verification:

[0133] The currently selected resistance is 100ppm. According to the resistance temperature drift coefficient R_ppm=100 / 1000000, the resistance temperature drift coefficient R_ppm=0.00001;

[0134] When the temperature is 125°C, the coefficient K = 1-(125-25)*0.00001 = 0.99;

[0135] When the temperature is -55°C, the coefficient K = 1-(-55-25)*0.00001 = 1.075;

[0136] It is basically consistent with the actual current acquisition temperature drift results.

[0137] Specifically, substitute formula (13) into formula (8) to obtain the compensation current I D

[0138]

[0139] Since the processor cannot perform decimal operations, the calculation of the decimal part is adjusted and the decimal is taken as the reciprocal: R_ppm is replaced by R_k, R_k = 1 / R_ppm, and the final compensation current I is obtained. D

[0140]

[0141] In the above formula (15), Tx and N X is a variable. Z is the compensation base, R_k is the reciprocal of the resistance temperature drift coefficient. The two parameters are stored in the parameter table of the processor. Subsequent projects can adjust the compensation base T according to different temperature sensors. Z, adjust R_K according to the temperature drift coefficient of the selected sampling resistor.

[0142] In addition, the MOS tube driver adopts the method of positive and negative voltage power supply, pulling the reference ground to -15V and increasing the potential difference, which can effectively improve the turn-off efficiency of the MOSFET, reduce the time that the MOSFET works in the linear region and the possible Miller oscillation time, and improve the durability of the MOSFET and the stability of the controller.

[0143] The current temperature compensation method of the current acquisition circuit of the solid-state power controller provided by the present invention has less calculation amount after simplification, does not require modeling or complex calculation, and the storage overhead is only the storage of the zero adjustment compensation base and the compensation coefficient. In addition, the method does not investigate the source of the output error caused by the existing temperature change, so that the algorithm has a wide range of application, the algorithm model is applicable to most temperature compensation scenarios, and the implementation is simple.

[0144] The current temperature compensation method of the current acquisition circuit of the solid-state power controller provided by the present invention greatly reduces the impact of product consistency caused by individual differences in components. As long as the above method can be implemented, the circuit structure can be varied.

[0145] Among the various circuit structures capable of implementing the above method, the present invention provides a current acquisition circuit.

[0146] like Figure 1 As shown, the present invention provides a current acquisition circuit for a solid-state power controller, comprising:

[0147] A power switch module, comprising a switch input terminal and a switch output terminal;

[0148] A current acquisition module, one end of which is located between the switch input end and the switch output end and connected to the power switch module, and the other end of the current acquisition module is connected to the MCU;

[0149] A switch driving module, one end of which is connected to the power switch module, and the other end of the switch driving module is connected to the MCU;

[0150] A temperature acquisition module connected to the MCU;

[0151] A communication module is connected to the MCU.

[0152] The present invention can process the entire compensation circuit of the power switch product as a black box, without investigating the source of the output error caused by the existing temperature change, and only compensates for the output deviation caused by the temperature change at the output end.

[0153] Based on the above situation, another embodiment, such as Figure 2As shown, the power switch module includes a power switch MOS tube, the drain of the power switch MOS tube is the switch input end, the source of the power switch MOS tube is connected to one end of the current acquisition module, and serves as the switch output end, and the gate of the power switch MOS tube is connected to the output end of the switch driving module.

[0154] The switching power supply module achieves stable voltage output through the conduction and shutdown of the MOS tube, and provides protection shutdown actions such as circuit breakers, overvoltages, and overcurrents.

[0155] Based on the above embodiments, specifically, Figure 2 As shown, the switch driving module includes a MOS driving chip, and the output end of the MOS driving chip is connected to the power switch module. Specifically, the output end of the MOS driving chip is connected to the gate of the power switch MOS tube, and the input end of the MOS driving chip is connected to the MCU. Through the PWM modulation waveform of the MCU, after being isolated and driven by the MOS tube driving unit, the on and off of the MOS tube is controlled as UGS.

[0156] Wherein, the MOS driver chip is powered by +15V and -15V.

[0157] The MOS tube driver chip adopts a positive and negative voltage power supply method to pull the reference ground to -15V. Regardless of whether the operational amplifier inside the MOS tube driver chip is rail-to-rail or non-rail-to-rail, its reference voltage value can be set to 0V through this power supply method. At the same time, the potential difference between the gate and the source during switching is increased, and the energy in the circuit during switching is discharged to the reference ground more quickly, thereby improving the turn-off efficiency of the MOSFET, reducing the time that the MOSFET works in the linear region, and the possible Miller oscillation time, improving the durability of the MOSFET and the stability of the controller, and preventing the tube from burning out; on the other hand, the MOS tube driver chip is powered by +15V and -15V, taking into account the withstand voltage between the gate and the source of the MOS tube.

[0158] Compared with the prior art (for example, increasing the resistance value of the G-pole control signal loop will reduce the Miller oscillation time), the MOS driver chip provided by the present invention avoids the problems of increasing the rise and fall time of the G-pole control signal and slowing down the switching speed, and also avoids the problem of selecting different resistance values ​​required for different systems.

[0159] Based on the above embodiments, specifically, Figure 2As shown, the current acquisition module includes a sampling resistor R and a differential amplifier, the input end of the sampling resistor R is connected between the switch input end and the switch output end, the output end of the sampling resistor is connected to one end of the differential amplifier, and the other end of the differential amplifier is connected to the MCU, and the model of the MCU is STM32F303CC.

[0160] Among them, the MCU is provided with an analog-to-digital converter, which is connected to the other end of the differential amplifier, and is used to quantify and perform related calculations on the standard voltage value (at room temperature) of the sampling resistor and the voltage value at the real-time temperature.

[0161] The differential amplifier is used to amplify the voltage value of the sampling resistor, and then quantize it through the ADC, and the temperature acquisition module performs compensation. If the sampling is done directly, since the small signal is at the millivolt level, it cannot reach about 2 / 3 of the ADC full scale. The purpose of amplification is to improve the sampling accuracy.

[0162] Based on the above embodiments, specifically, Figure 2 As shown, the temperature acquisition module includes a temperature sensor, which is connected to an analog-to-digital converter in the MCU. The analog-to-digital converter is used to quantify the voltage value of the temperature sensor and the sampling resistor.

[0163] The temperature sensor is mainly used to collect the temperature value of the current environment inside the controller for display and to participate in the calculation as the standard temperature value of the compensation algorithm. The MCU contains a storage device, and the temperature zero point data is stored here.

[0164] Specifically, it also includes a communication module, which includes a 485 isolation drive module and a host computer, wherein the 485 isolation drive module is connected to the MCU, and the host computer is connected to the 485 isolation drive module. The communication module realizes the drive of the digital isolation communication signal and provides RS485 communication between the controller MCU and the host computer, that is, to realize the functions of display, configuration, monitoring, etc.

[0165] Here, the implementation endpoint of the algorithm is the display of the host computer program. The temperature of the input power supply will not change by default, but the temperature of the solid-state power controller will rise to a certain extent due to the heat generated by line loss. In addition, its working environment is relatively harsh. In monitoring and display, the deviation caused by the temperature drift characteristics of the device cannot be ignored. The algorithm based on temperature calibration only adjusts the display and monitoring, and does not change the actual output current value of the power switch module.

[0166] In the current acquisition circuit of the above-mentioned solid-state power controller, R is a sampling resistor with a fixed temperature drift coefficient located in the switching power supply path. The voltage across the resistor is amplified by a differential operational amplifier and sampled by the ADC of the MCU as a reference value for output current temperature compensation. The temperature sensor T provides the standard ambient temperature. The MOSFET drive module is powered by +15V and -15V to increase the level pull-down speed when the MOSFET is turned off.

[0167] In addition, the present invention provides a MOSFET U GS Waveform diagram, specifically, when the MOSFET driver chip uses -15V as the reference ground, the U GS Waveform Figure 4 As shown in the figure, for comparison, when the MOSFET driver chip uses 0V as the reference ground, the U GS Waveform Figure 3 It shows the waveform edge characteristics of Miller oscillation when 0V is used as the reference ground. Figure 4 It can be clearly seen that the oscillation phenomenon is greatly improved when -15V is used as the reference ground.

[0168] It is obvious that those skilled in the art can obtain various effects that have not been directly mentioned according to the various embodiments from the various structures according to the embodiments of the present invention.

[0169] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and the embodiments. It can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily realized. Therefore, without departing from the general concept defined by the claims and equivalent scope, the present invention is not limited to the specific details and the illustrations shown and described here.

Claims

1. A current acquisition circuit for a solid-state power controller, characterized in that: include: A power switch module, comprising a switch input terminal and a switch output terminal; A current acquisition module, one end of which is located between the switch input end and the switch output end and connected to the power switch module, and the other end of the current acquisition module is connected to the MCU; A switch driving module, one end of which is connected to the power switch module, and the other end of the switch driving module is connected to the MCU; A temperature acquisition module connected to the MCU; A communication module connected to the MCU; The MCU is configured to perform: Set the compensation zero point, and use the resistance value of the sampling resistor under the compensation zero point as the standard value; Calculating the ratio of the resistance value of the sampling resistor at the real-time temperature to the standard value, and defining the ratio as a compensation coefficient of the output current; The temperature acquisition module is used to obtain the compensation current at the real-time temperature by combining the output current value of the sampling resistor at the real-time temperature, the compensation coefficient, and the quantized voltage value of the sampling resistor.

2. The current acquisition circuit of the solid-state power controller according to claim 1, characterized in that: The power switch module includes a power switch MOS tube, the drain of the power switch MOS tube is the switch input end, the source of the power switch MOS tube is connected to one end of the current acquisition module and serves as the switch output end, and the gate of the power switch MOS tube is connected to the output end of the switch driving module.

3. The current acquisition circuit of the solid-state power controller according to claim 1, characterized in that: The switch driving module comprises a MOS driving chip, the output end of the MOS driving chip is connected to the power switch module, and the input end of the MOS driving chip is connected to the MCU; Wherein, the MOS driver chip is powered by +15V and -15V.

4. The current acquisition circuit of the solid-state power controller according to claim 1, characterized in that: The current acquisition module includes a sampling resistor and a differential amplifier, wherein the input end of the sampling resistor is connected between the switch input end and the switch output end, the output end of the sampling resistor is connected to one end of the differential amplifier, and the other end of the differential amplifier is connected to the MCU; an analog-to-digital converter is provided in the MCU, and the analog-to-digital converter is connected to the other end of the differential amplifier; The temperature acquisition module includes a temperature sensor, which is connected to an analog-to-digital converter in the MCU. The analog-to-digital converter is used to quantify the voltage value of the temperature sensor and the sampling resistor.

5. A current temperature compensation method for a current acquisition circuit of a solid-state power controller according to any one of claims 1 to 4, characterized in that: The method comprises: Set the compensation zero point, and use the resistance value of the sampling resistor under the compensation zero point as the standard value; Calculating the ratio of the resistance value of the sampling resistor at the real-time temperature to the standard value, and defining the ratio as a compensation coefficient of the output current; The temperature acquisition module is used to obtain the compensation current at the real-time temperature by combining the output current value of the sampling resistor at the real-time temperature, the compensation coefficient, and the quantized voltage value of the sampling resistor.

6. The current temperature compensation method of the current acquisition circuit of the solid-state power controller according to claim 5, characterized in that: It also includes compensation and zero adjustment of the temperature acquisition module: At the compensation zero point, the voltage value corresponding to the temperature acquisition module is quantized after being sampled by an analog-to-digital converter provided in the MCU to obtain a compensation base; At real-time temperature, the voltage value corresponding to the temperature acquisition module is quantized after being sampled by an analog-to-digital converter set in the MCU to obtain a real-time temperature quantization value; The compensation coefficient is optimized by combining the compensation base and the real-time temperature quantization value to obtain a final compensation coefficient.

7. The current temperature compensation method of the current acquisition circuit of the solid-state power controller according to claim 6, characterized in that: The calculating the ratio of the resistance value of the sampling resistor at the real-time temperature to the standard value, and defining the ratio as a compensation coefficient of the output current, specifically includes: At the real-time temperature T, the resistance of the sampling resistor is R X for R X =R 25 -[(T-25℃)*R_ppm*R 25 ] (1) According to the ratio of the resistance value of the sampling resistor to the standard value, the compensation coefficient K of the output current is obtained. K=R X / R 25 (2) According to (1) and (2), the output current compensation coefficient K can be obtained. K=1-((T-25℃)*R_ppm) (3) Among them, the normal temperature (25℃) is set as the compensation zero point, R_ppm is the temperature drift coefficient of the sampling resistor, R 25 To compensate the resistance value of the sampling resistor under zero point.

8. The current temperature compensation method of the current acquisition circuit of the solid-state power controller according to claim 6, characterized in that: The compensation current at the real-time temperature is obtained by combining the output current value of the sampling resistor at the real-time temperature, the compensation coefficient, and the quantized voltage value of the sampling resistor through the temperature acquisition module, including: At the real-time temperature T, the voltage difference across the sampling resistor is sampled to obtain ΔV x According to Ohm's law, the compensated current value I D I D =ΔV X / R X (4) Substituting formula (2) into formula (4), we can obtain: I D =ΔV X / (R 25 *K) (5) ΔV x After being amplified by the differential amplifier, it becomes ΔV x *α, and then sampled by the analog-to-digital converter set in the MCU to obtain the quantized value N X , and the difference ΔV across the sampling resistor can be obtained by inverse quantization. x ΔV X =N X *U m / [(2 n -1)*a] (6) Substituting (6) into (5), the output current after compensation is I D I D ={N X *U m / [(2 n -1)*α]} / ((R 25 *K)) (7) The product term {U m / [(2 n -1)*α*R 25 ) is the current sampling resolution. By taking this part out, we can get Among them, suppose the effective number of bits of the analog-to-digital converter is n, U m Maximum range 2 n -1, and α is the closed-loop gain of the differential amplifier.

9. The current temperature compensation method of the current acquisition circuit of the solid-state power controller according to claim 8, characterized in that: It also includes the setting of compensation zero point of temperature acquisition module: When setting the compensation zero point, the voltage value corresponding to the temperature acquisition module is V Z , the compensation base after sampling by the MCU's analog-to-digital converter is T Z , which is stored in the MCU after manual measurement at 25°C; At real-time temperature, the real-time temperature quantization value sampled by MCU is Tx, and the temperature characteristic voltage value V input to MCU X It can be obtained by inverse quantization calculation: V X =U m *T X / (2 n -1) (9) The voltage and temperature change relationship of the temperature acquisition module used is linearly positively correlated. The proportional coefficient of temperature T and voltage V is set to β. According to formula (9), we get T=β*V X (10) Substituting Vx in equation (10) into equation (9), we get the real-time temperature T T=β*U m *T X / (2 n -1) (11) T in formula (11) X Available T X -T Z replace: T-25℃=β*U m *(T X -T Z ) / (2 n -1) (12) Substituting (12) into (3), we get the current compensation coefficient K1: K1=1-[β*U m *(T X -T Z ) / (2 n -1)]*R_ppm (13)。 10. The current temperature compensation method of the current acquisition circuit of the solid-state power controller according to claim 9, characterized in that: Substituting formula (13) into formula (8), we can get the compensation current I D Since the MCU does not support floating-point operations, R_ppm is replaced by R_k, so that R_k = 1 / R_ppm, and the compensation current I is obtained. D for

Images