Integrated current measurement circuit

Abstract

An integrated current measurement circuit, relating to the field of current measurement technology, effectively reduces circuit components, alleviates the limitations of high-voltage layout, enhances the circuit's anti-interference capability, and lowers costs. In the integrated current measurement circuit, the measured current flows into MOTOR_V_IP+ and out of MOTOR_V_IP-. The Hall sensor inside the NSM2015 chip measures the current information and transmits it as a unipolar voltage signal output by MI_ADC_V_VOUT_1. Pin 12 of the NSM2015 is connected to bypass capacitor C185, and the other end is connected to GND. After bypass filtering, the signal is sent to the unipolar ADC for sampling. A zero-current reference voltage output is connected to bypass capacitor C184, and the other end is connected to GND. After bypass filtering, the signal is sent to the unipolar ADC for sampling.

Description

Technical Field

[0001] This utility model relates to the field of current measurement technology, and in particular to an integrated current measurement circuit. Background Technology

[0002] Currently, most solutions on the market that use series milliohm sampling resistors to indirectly measure current use voltage isolation devices to transfer the voltage across the milliohm resistor to the isolated low-voltage side. Since the current is a bidirectional differential signal, an operational amplifier is needed to convert the signal into a single-ended signal for easy sampling by a single-ended ADC. Furthermore, for the sake of fast overcurrent protection, a comparator is also needed to provide an overcurrent signal.

[0003] Specifically, the sampling resistor on the high-voltage side needs to withstand power surges (high resistance requirements) and be isolated. Since sufficient safety and creepage distances must be provided on the high-voltage side, a large area on the PCB is needed to avoid the components (layout constraints). The low-voltage test requires an operational amplifier and a comparator to process the signal. For high precision, an additional reference source is needed to accurately measure the overcurrent point.

[0004] In summary, the existing technology has the following main shortcomings:

[0005] (1) Due to series resistance sampling, the thermal stability of the resistor is required to be extremely high. Errors caused by the thermal stability of the resistor affect the measurement accuracy.

[0006] (2) The sampled voltage signal is a small voltage signal. Since the measured output current is all switched SVPWM modulation, the interference is very large. The small voltage signal line is easily interfered with, and the measurement error is very large.

[0007] (3) Low-voltage side signal transmission requires additional operational amplifiers and comparators, which increases costs;

[0008] (4) An additional 5V power supply circuit (i.e., a 5.1V Zener diode) is required on the high-voltage side. Utility Model Content

[0009] The purpose of this invention is to provide an integrated current measurement circuit that effectively reduces the number of circuit components, alleviates the limitations of high-voltage layout, enhances the circuit's anti-interference capability, and reduces costs.

[0010] To achieve the above objectives, the present invention adopts the following technical solution:

[0011] An integrated current measurement circuit includes: a Nanochip NSM2015 device, six capacitors, three resistors, and PCB traces.

[0012] The measured current flows into MOTOR_V_IP+, i.e., pins 1, 2, 3, and 4 of NSM2015, and flows out from MOTOR_V_IP-, i.e., pins 5, 6, 7, and 8 of NSM2015. The Hall sensor inside the NSM2015 chip measures the current information and converts it into a unipolar voltage signal, which is output by MI_ADC_V_VOUT_1, i.e., pin 12 of NSM2015. Pin 12 of NSM2015 is connected to a bypass capacitor C185, and the other end is connected to GND. After bypass filtering, the signal is sent to the unipolar ADC for sampling.

[0013] The zero-current reference voltage output, i.e., pin 13 of the NSM2015, is connected to bypass capacitor C184, and the other end is connected to GND. After bypass filtering, it is sent to the unipolar ADC for sampling.

[0014] The chip's power supply pin, also known as pin 10 of the NSM2015, is connected to parallel capacitors C186 and C187. The other end of the parallel connection is connected to GND for power supply bypass filtering.

[0015] The chip's overcurrent point configuration is achieved through an external voltage configuration VOC, i.e., setting the overcurrent point on pin 11 of the NSM2015. The zero current reference voltage 2.5V pin, i.e., pin 13 of the NSM2015, is connected to resistor R171, and the other end is connected to resistor R173 in parallel with capacitor C188. The other end of the parallel connection is connected to GND. The series resistors divide the voltage to 2.5V to configure VOC, i.e., pin 11 of the NSM2015, which is 1V, i.e., the 100%FS range point overcurrent.

[0016] When the current exceeds the overcurrent point MI_V_FAULT, that is, the NSM2015 outputs a low signal on pin 9 to indicate overcurrent. Pin 9 of the NSM2015 is connected to a resistor R172 for pull-up and connected to a 5V power supply. In order to prevent interference, pin 9 of the NSM2015 is connected to a capacitor C189, and the other end is connected to GND for bypass filtering.

[0017] In practical applications, capacitor C185 is 1nF, capacitor C184 is 1nF, capacitor C186 is 100nF, capacitor C187 is 1uF, capacitor C188 is 100nF, and capacitor C189 is 1nF.

[0018] Wherein, resistor R171 is 10kΩ and resistor R173 is 6.4kΩ.

[0019] Specifically, the NSM2015 device from Nanochip Microelectronics includes: a current Hall sensor, a sensor excitation circuit, a differential signal transmitter circuit, a baseline lift circuit, an overcurrent comparator, a regulated voltage, and a temperature sensor.

[0020] Compared with the prior art, the integrated current measurement circuit of this utility model has the following advantages:

[0021] The integrated current measurement circuit provided by this invention employs differential Hall effect measurement internally to resist interference from external stray magnetic fields, eliminating the high power requirements of the sampling resistor and the interference of the low-voltage signal sampling loop. It integrates a signal processing and transmission unit, eliminating the need for an operational amplifier and a comparator, thus reducing the number of high-voltage side components and improving the high-voltage layout environment. The fast overcurrent output provides a simple method for detecting overload and short-circuit events, preventing damage to power transistors in inverters and motors. It also eliminates the need for a high-voltage side power supply circuit. Therefore, the integrated current measurement circuit provided by this invention effectively reduces circuit components, alleviates the limitations of high-voltage layout, enhances the circuit's anti-interference capability, and lowers costs. Attached Figure Description

[0022] Figure 1 A schematic diagram of the integrated current measurement circuit provided in this embodiment of the present invention;

[0023] Figure 2 A schematic diagram of the structure of the NSM2015 device in the integrated current measurement circuit provided in this embodiment of the present invention. Detailed Implementation

[0024] For ease of understanding, the integrated current measurement circuit provided in the embodiments of this utility model will be described in detail below with reference to the accompanying drawings.

[0025] This utility model embodiment provides an integrated current measurement circuit, such as Figure 1 As shown, it includes: a Nanochip NSM2015 device, six capacitors, three resistors, and PCB traces;

[0026] The measured current flows into MOTOR_V_IP+, i.e., pins 1, 2, 3, and 4 of NSM2015, and flows out from MOTOR_V_IP-, i.e., pins 5, 6, 7, and 8 of NSM2015. The Hall sensor inside the NSM2015 chip measures the current information and converts it into a unipolar voltage signal, which is output by MI_ADC_V_VOUT_1, i.e., pin 12 of NSM2015. Pin 12 of NSM2015 is connected to a bypass capacitor C185, and the other end is connected to GND. After bypass filtering, the signal is sent to the unipolar ADC for sampling.

[0027] The zero-current reference voltage output, i.e., pin 13 of the NSM2015, is connected to bypass capacitor C184, and the other end is connected to GND. After bypass filtering, it is sent to the unipolar ADC for sampling.

[0028] The chip's power supply pin, also known as pin 10 of the NSM2015, is connected to parallel capacitors C186 and C187. The other end of the parallel connection is connected to GND for power supply bypass filtering.

[0029] The chip's overcurrent point configuration is achieved through an external voltage configuration VOC, i.e., setting the overcurrent point on pin 11 of the NSM2015. The zero current reference voltage 2.5V pin, i.e., pin 13 of the NSM2015, is connected to resistor R171, and the other end is connected to resistor R173 in parallel with capacitor C188. The other end of the parallel connection is connected to GND. The series resistors divide the voltage to 2.5V to configure VOC, i.e., pin 11 of the NSM2015, which is 1V, i.e., the 100%FS range point overcurrent.

[0030] When the current exceeds the overcurrent point MI_V_FAULT, that is, the NSM2015 outputs a low signal on pin 9 to indicate overcurrent. Pin 9 of the NSM2015 is connected to a resistor R172 for pull-up and connected to a 5V power supply. In order to prevent interference, pin 9 of the NSM2015 is connected to a capacitor C189, and the other end is connected to GND for bypass filtering.

[0031] Compared with the prior art, the integrated current measurement circuit described in this embodiment of the present invention has the following advantages:

[0032] The integrated current measurement circuit provided in this embodiment of the invention employs differential Hall effect measurement internally to resist interference from external stray magnetic fields, eliminating the high power requirements of the sampling resistor and the interference of the low-voltage signal sampling loop. It integrates a signal processing and transmission unit, eliminating the need for an operational amplifier and a comparator, thus reducing the number of high-voltage side components and improving the high-voltage layout environment. The fast overcurrent output provides a simple method for detecting overload and short-circuit events, preventing damage to power transistors in inverters and motors. It also eliminates the need for a high-voltage side power supply circuit. Therefore, the integrated current measurement circuit provided by this invention effectively reduces circuit components, alleviates the limitations of high-voltage layout, enhances the circuit's anti-interference capability, and lowers costs.

[0033] In practical applications, such as Figure 1 As shown, capacitor C185 can be 1nF, capacitor C184 can be 1nF, capacitor C186 can be 100nF, capacitor C187 can be 1uF, capacitor C188 can be 100nF, and capacitor C189 can be 1nF.

[0034] Among them, such as Figure 1 As shown, the resistor R171 can be 10kΩ and the resistor R173 can be 6.4kΩ.

[0035] Specifically, such as Figure 2 As shown, the above-mentioned NSM2015 device from Nanochip Microelectronics may include: a current Hall sensor (1, 2), a sensor excitation circuit (3), a differential signal transmission circuit (4, 5), a baseline lifting circuit (6), an overcurrent comparator (7), a regulated voltage (8), and a temperature sensor (9).

[0036] Furthermore, the common-mode radiated electric field strength is: E = 12.6 x 10⁻⁶. -7 fIL / r;

[0037] Interference is proportional to the area of ​​the measurement current loop. The creepage and insulation distance requirements for the 800V platform are at least 7mm. No matter how the traces are routed, the loop area cannot be small. However, the size of the integrated device is much smaller than the loop area, so the anti-interference capability is significantly stronger than the traditional series resistor solution.

[0038] In summary, the integrated current measurement circuit provided by this utility model embodiment has the following advantages:

[0039] I. Circuit Topology of Application: It replaces onboard current measurement solutions below 100A, with high integration, high stability, high isolation level, fast overcurrent protection, smaller package, and reduced solution cost;

[0040] 2. Configuration of overcurrent protection voltage value (per unit ratio): This overcurrent voltage value VOC is the per unit ratio of the circuit parameters. For different currents, you only need to change the measurement range of the NSM2015 device, without adjusting the transmission ratio.

[0041] The above description is merely a specific embodiment of this utility model, but the protection scope of this utility model 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 utility model should be included within the protection scope of this utility model. Therefore, the protection scope of this utility model should be determined by the protection scope of the claims.

Claims

1. An integrated current measurement circuit, characterized in that, include: The device is a Nanochip NSM2015, consisting of six capacitors, three resistors, and PCB traces. The measured current flows into MOTOR_V_IP+, i.e., pins 1, 2, 3, and 4 of NSM2015, and flows out from MOTOR_V_IP-, i.e., pins 5, 6, 7, and 8 of NSM2015. The Hall sensor inside the NSM2015 chip measures the current information and converts it into a unipolar voltage signal, which is output by MI_ADC_V_VOUT_1, i.e., pin 12 of NSM2015. Pin 12 of NSM2015 is connected to a bypass capacitor C185, and the other end is connected to GND. After bypass filtering, the signal is sent to the unipolar ADC for sampling. The zero-current reference voltage output, i.e., pin 13 of the NSM2015, is connected to bypass capacitor C184, and the other end is connected to GND. After bypass filtering, it is sent to the unipolar ADC for sampling. The chip's power supply pin, also known as pin 10 of the NSM2015, is connected to parallel capacitors C186 and C187. The other end of the parallel connection is connected to GND for power supply bypass filtering. The chip's overcurrent point configuration is achieved through an external voltage configuration VOC, i.e., setting the overcurrent point on pin 11 of the NSM2015. The zero current reference voltage 2.5V pin, i.e., pin 13 of the NSM2015, is connected to resistor R171, and the other end is connected to resistor R173 in parallel with capacitor C188. The other end of the parallel connection is connected to GND. The series resistors divide the voltage to 2.5V to configure VOC, i.e., pin 11 of the NSM2015, which is 1V, i.e., the 100%FS range point overcurrent. When the current exceeds the overcurrent point MI_V_FAULT, that is, the NSM2015 outputs a low signal on pin 9 to indicate overcurrent. Pin 9 of the NSM2015 is connected to a resistor R172 for pull-up and connected to a 5V power supply. In order to prevent interference, pin 9 of the NSM2015 is connected to a capacitor C189, and the other end is connected to GND for bypass filtering.

2. The integrated current measurement circuit according to claim 1, characterized in that, The capacitor C185 is 1nF, the capacitor C184 is 1nF, the capacitor C186 is 100nF, the capacitor C187 is 1uF, the capacitor C188 is 100nF, and the capacitor C189 is 1nF.

3. The integrated current measurement circuit according to claim 1, characterized in that, The resistor R171 is 10kΩ and the resistor R173 is 6.4kΩ.

4. The integrated current measurement circuit according to any one of claims 1-3, characterized in that, The NSM2015 device from Nanochip Microelectronics includes: a current Hall sensor, a sensor excitation circuit, a differential signal transmission circuit, a baseline lift circuit, an overcurrent comparator, a regulated voltage, and a temperature sensor.

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