阅读说明：本技术 一种电流测量方法、电路以及使用该电路的装置 (Current measuring method, circuit and device using circuit ) 是由 杨勇 黄科 苗小雨 陈晓 周彦 李振华 于 2020-12-10 设计创作，主要内容包括：本发明提供一种电流测量方法、电路及电子装置。具体技术方案为：将电源与第一P型MOS管漏极连接；将第一P型MOS管、第一负载、第一电阻串行连接；将第一驱动器与所述第一P型MOS管栅极连接；所述第一驱动器产生周期信号,所述周期信号控制所述第一P型MOS管周期性地导通断开；将第一测量单元连接于所述第一电阻两端；在所述第一P型MOS管断开周期,所述第一测量单元输出内部电流,所述内部电流流经所述第一电阻,所述测量单元输出测量电压V1；在所述第一P型MOS管导通周期,流经所述第一P型MOS管、第一负载、第一电阻的电流相同,所述测量单元输出测量电压V2。本发明可准确检测系统工作电流,从而实现准确的过流保护以及功率控制,又能有效降低方案成本。(The invention provides a current measuring method, a circuit and an electronic device. The specific technical scheme is as follows: connecting a power supply with a drain electrode of the first P-type MOS tube; connecting a first P-type MOS tube, a first load and a first resistor in series; connecting a first driver with the grid electrode of the first P-type MOS tube; the first driver generates periodic signals, and the periodic signals control the first P-type MOS tube to be periodically switched on and off; connecting a first measuring unit to two ends of the first resistor; in the off period of the first P-type MOS tube, the first measuring unit outputs an internal current, the internal current flows through the first resistor, and the measuring unit outputs a measuring voltage V1; in the conduction period of the first P-type MOS tube, the currents flowing through the first P-type MOS tube, the first load and the first resistor are the same, and the measuring unit outputs a measuring voltage V2. The invention can accurately detect the working current of the system, thereby realizing accurate overcurrent protection and power control and effectively reducing the scheme cost.)

1. A current measuring method, characterized by: connecting a power supply with a drain electrode of the first P-type MOS tube;

connecting a first P-type MOS tube, a first load and a first resistor in series;

connecting a first driver with the grid electrode of the first P-type MOS tube;

the first driver generates periodic signals, and the periodic signals control the first P-type MOS tube to be periodically switched on and off;

connecting a first measuring unit to two ends of the first resistor;

in the off period of the first P-type MOS tube, the first measuring unit outputs an internal current, the internal current flows through the first resistor, and the measuring unit outputs a measuring voltage V1;

in the conduction period of the first P-type MOS tube, the currents flowing through the first P-type MOS tube, the first load and the first resistor are the same, and the measuring unit outputs a measuring voltage V2;

the first calculating unit is used for calculating the current flowing through the first load in the first P-type MOS tube conduction period according to the measuring voltages V1 and V2.

2. A circuit, characterized by: the device comprises a first P-type MOS tube, a power supply, a first load, a first resistor, a first driver, a first measuring unit and a first calculating unit;

the power supply is connected with the drain electrode of the first P-type MOS tube;

the first P-type MOS tube, the first load and the first resistor are connected in series;

the first driver is connected with the grid electrode of the first P-type MOS tube;

the first driver generates periodic signals, and the periodic signals control the first P-type MOS tube to be periodically switched on and off;

the first measuring unit is connected to two ends of the first resistor;

in the off period of the first P-type MOS tube, the first measuring unit outputs an internal current, the internal current flows through the first resistor, and the measuring unit outputs a measuring voltage V1;

in the conduction period of the first P-type MOS tube, the currents flowing through the first P-type MOS tube, the first load and the first resistor are the same, and the measuring unit outputs a measuring voltage V2;

the first calculating unit is used for calculating the current flowing through the first load in the first P-type MOS tube conduction period according to the measuring voltages V1 and V2.

3. A circuit according to claim 2, wherein: the system also comprises a first controller;

the first arithmetic processing unit is connected with the first controller and receives signals of the first arithmetic processing unit;

and when the signal received by the first controller is greater than a first threshold value, the first driver is controlled to output a signal for disconnecting the first P-type MOS tube.

4. A circuit according to claim 2, wherein: the device also comprises a first analog-to-digital converter and a first controller;

the first analog-to-digital converter is connected with the first operation processing unit;

the first analog-to-digital converter converts an output signal of the first operation processing unit into a digital signal;

the first controller receives a digital signal of the first analog-to-digital converter;

the first controller controls the duty ratio of the periodic signal generated by the first driver according to the digital signal.

5. An electronic device, characterized in that: current measurement is performed using a circuit as claimed in claim 2.

6. An electronic device, characterized in that: use of a circuit according to claim 3 for overcurrent protection.

7. An electronic device, characterized in that: use of a circuit as claimed in claim 4 for power control.

Technical Field

The invention belongs to the field of electronic circuits, and particularly relates to a current measuring method, a current measuring circuit and a device using the current measuring circuit.

Background

Application scenarios such as e-cigarettes require precise control of current, power in order to achieve a good user experience. In the prior art, the current and the voltage are generally measured through known resistances. The measurement of the current requires that the characteristics of the sampling resistor (Rs) are stable (such as temperature characteristics and voltage characteristics), the temperature characteristics of the resistor may change under high-temperature application such as an electronic cigarette, and the actual value of the resistor deviates from a preset value, and at the same time, the sampling resistors in different batches have good consistency, for example, different resistors in the same batch have certain quality deviation, if the preset values of the resistors are all set to be the same, part of products may be unqualified, which increases the design difficulty and the cost pressure of the system scheme.

Disclosure of Invention

In order to solve the technical problems, the invention provides a circuit and an electronic device, which reduce the dependence on the resistance precision and the scheme cost of a monitoring system through sampling detection.

The invention provides a circuit for measuring current, which comprises a first P-type MOS tube, a power supply, a first load, a first resistor, a first driver, a first measuring unit and a first calculating unit, wherein the first P-type MOS tube is connected with the power supply; the power supply is connected with the drain electrode of the first P-type MOS tube; the first P-type MOS tube, the first load and the first resistor are connected in series; the first driver is connected with the grid electrode of the first P-type MOS tube; the first driver generates periodic signals, and the periodic signals control the first P-type MOS tube to be periodically switched on and off; the first measuring unit is connected to two ends of the first resistor; in the off period of the first P-type MOS tube, the first measuring unit outputs an internal current, the internal current flows through the first resistor, and the measuring unit outputs a measuring voltage V1; in the conduction period of the first P-type MOS tube, the currents flowing through the first P-type MOS tube, the first load and the first resistor are the same, and the measuring unit outputs a measuring voltage V2; the first calculating unit is used for calculating the current flowing through the first load in the first P-type MOS tube conduction period according to the measuring voltages V1 and V2.

Preferably: the overcurrent protection circuit is also provided, and the overcurrent protection circuit further comprises a first controller on the basis of the current measurement circuit; the first arithmetic processing unit is connected with the first controller and receives signals of the first arithmetic processing unit; and when the signal received by the first controller is greater than a first threshold value, the first driver is controlled to output a signal for disconnecting the first P-type MOS tube.

Preferably: the power control circuit is further provided, and the power control circuit further comprises a first analog-to-digital converter and a first controller on the basis of the current measuring circuit; the first analog-to-digital converter is connected with the first operation processing unit; the first analog-to-digital converter converts an output signal of the first operation processing unit into a digital signal; the first controller receives a digital signal of the first analog-to-digital converter; the first controller controls the duty ratio of the periodic signal generated by the first driver according to the digital signal.

Preferably: an electronic device is also provided, and the circuit is used for current measurement, overcurrent protection and power control.

The invention has the beneficial effects that: the system can select a sampling resistor with low precision, the detection system can firstly measure the sampling resistor, and the system can detect the system current in real time when the system works normally. The system working current can be accurately detected, so that accurate overcurrent protection and power control are realized, and the scheme cost can be effectively reduced.

Drawings

The above and other objects, features and advantages of the present invention will become more apparent from the following description of the embodiments of the present invention with reference to the accompanying drawings.

FIG. 1 is a current measurement circuit;

FIG. 2 shows another method of measuring the series connection of the resistor, load, and PMOS transistors;

FIG. 3 is an overcurrent protection circuit;

fig. 4 power control circuit.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Unless otherwise specified, the technical means used in the examples are conventional means well known to those skilled in the art.

In the description of the present invention, it is to be understood that the terms "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like, indicate orientations or positional relationships based on those shown in the drawings, are merely for convenience of description of the present invention, and do not indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and thus, are not to be construed as limiting the present invention.

As shown in fig. 1, the P1 device is a P-type MOS transistor for controlling the current flowing through the load. As shown in fig. 1, the load Sys and the measurement resistor Rs1 are both connected in series with P1, and the load Sys and the measurement resistor Rs1 are not limited in position and may be both connected in series at the drain, or both connected in series at the source, as shown in fig. 2, or one of the source and the drain. Due to the series relationship, when the P1 is conducted, the current flowing through the P1, the Sys and the Rs1 is the same.

When the current flowing through the load Sys when the P1 is turned on is set to be Ip1, it is important how to accurately detect the magnitude of the current flowing through the Ip1 device in practical applications, for example, power control, overcurrent protection, etc. are all based on the accurate Ip 1. As shown in fig. 1, the gate signal G generated by Driver is a clock signal, the period of the signal remains unchanged, for example, during t1, the P1 device is turned off, during t2, the P1 device is turned on, during t1, the P1 device is turned on, and during t2, the P1 device is turned off, as long as the on/off signal of the periodic signal conforms to the PMOS switching principle.

Illustratively, P1 is turned off during t1, so the current flowing through Sys and Rs1 is 0, the measurement unit "Rs 1 Measure" outputs an internal high precision current ICC across Rs1, and the Rs1 port voltage is multiplied by an internal cell coefficient α, which is set by the "Rs 1 Measure" internal high precision current ICC in the practical detection system application, to obtain the "Rs 1 Measure" unit output voltage Vxt1 α ICC Rs1 during t 1.

Illustratively, during t2, P1 is turned on, so that a current flows through a series system of P1, Sys1 and Rs1, and if the current flowing through Sys1 and Rs1 is Ip1, the measurement unit "Rs 1 Measure" unit can detect the terminal voltage of Rs1, and the terminal voltage is multiplied by a unit internal coefficient β, so as to obtain the "Rs 1 Measure" unit output voltage Vxt2 ═ Ip1 × Rs1 during t2, wherein the unit internal coefficient β is set by the "Rs 1 Measure" unit, and the coefficient can be set within a reasonable range according to the magnitude of the protection system current gear.

Illustratively, the gate signals G generated by the Driver are sampled by the Vxt1, Vxt2, and specifically, the gate signals G generated by the Driver are also input to a scalar operation processor unit (not shown in fig. 1) which synchronously reads the output voltage of the "Rs 1 Measure" unit according to the signals G, namely Vxt1 during t1 and Vxt2 during t 2.

Alternatively, Vxt1 is the average voltage during t1, and Vxt2 is the average voltage during t 2.

Alternatively, Vxt1 is the highest voltage during t1, and Vxt2 is the highest voltage during t 2.

Illustratively, Vxt1, Vxt2 may be sampled by absolute magnitude, specifically, when the voltage output by the "Rs 1 Measure" cell is less than Vr1, it is considered during t1, and when the voltage output by the "Rs 1 Measure" cell is greater than Vr2, it is considered during t 2.

Alternatively, Vxt1 is an average voltage less than Vr1 and Vxt2 is an average voltage greater than Vr 2.

Alternatively, Vxt1 is the lowest voltage less than Vr1 and Vxt2 is the highest voltage greater than Vr 2.

After obtaining vx 1 ═ α ICC Rs1 and vx 2 ═ β Ip1 Rs1, we can derive Ip1 ═ vx 2 [ (. α × ICC)/(β vx 1) by dividing the two sides of the equation, we can see that here resistor Rs1 has been eliminated, we can see that the measured Ip1 is independent of Rs1, α, β, ICC, Vxt1, Vxt2 are known, we can see that by measuring and calculating Vtx1, Vtx2, we can find P1 device current in the system, and the current is no longer related to resistance accuracy, which can be used for subsequent overcurrent protection and power control, and we can achieve more accurate effect.

To calculate Ip1, a further sealer arithmetic processor unit is connected to the measurement unit "Rs 1 Measure", receives the voltage signal output by the measurement unit "Rs 1 Measure", and calculates the current Ip1 through the load system Sys1 using the above calculation method.

Specifically, the Calculator arithmetic processor unit holds the voltage Vtx1 output by "Rs 1 Measure" during t 1; during t2 the sealer arithmetic processor unit receives Vtx2 output by the measurement unit "Rs 1 Measure" and calculates the current through the load from Ip1 ═ xt2 × (α × ICC)/(β × xt 1). The Calculator arithmetic processor unit continuously calculates Ip1 and generates an output signal for subsequent modules according to the calculation result.

Further, the signal output by the scaler operation processor unit may be an analog signal indicating the size of Ip1, a square wave signal subjected to waveform processing, or a digital signal obtained by performing analog-to-digital conversion on an analog signal indicating the size of Ip 1.

On the basis of the embodiment, further, over-current protection can be performed on the system on the basis of obtaining the accurate current.

As shown in fig. 3, the Calculator arithmetic processor unit is connected to the Controller unit, and the Controller unit receives the output signal of the Calculator arithmetic processor unit, determines the output signal, and if the output signal is greater than the threshold, it indicates that the current is too large, and overcurrent protection is required.

In one implementation, the Calculator arithmetic processor unit outputs an analog signal indicating the size of Ip1, for example, a waveform signal generated according to the actual size of Ip1, the Controller sets a threshold, and when the signal is greater than the threshold, the Controller controls the Driver unit to continuously output a signal for controlling the P1 to be turned off, so as to protect the load.

Further, in order to prevent misjudgment, the Controller may set that the Controller considers that the overcurrent is detected when the duration T is greater than the threshold, and then triggers the overcurrent protection. The time T here may be specifically set according to the actual performance of the load, and a specific value is not given in this embodiment.

In one implementation, the Calculator arithmetic processor unit outputs a digital signal indicating the size of Ip1, for example, if Ip1 is greater than a first threshold, 1 is output, and if it is less than a second threshold, 0 is output, and if 1 is output continuously, the Controller unit controls the Driver unit to continuously output a signal for controlling P1 to be turned off, so as to protect the load.

On the basis of the foregoing embodiments, further, the system may also be power controlled. As shown in fig. 4, the Calculator processor outputs an analog signal, and the ADC module digitizes the current signal after receiving the current signal from the Calculator processor unit, for example, if Ip is greater than a first threshold, 1 is output, and if Ip is less than a second threshold, 0 is output.

Illustratively, different "ADC" outputs are set corresponding to the duty cycle of the "scaler" unit output clock signal Sco, such as setting the duty cycle to 50% when the initial average Ip1 is 10A, with 0 and 1 each being half, and when the average Ip1 is 10.5A, the duty cycle of the Sco signal is adjusted to 55% according to the "ADC" unit output. Under the condition of constant G signal period, adjusting t1/(t1+ t2) can control the density of P1 transmitted energy, thereby keeping the load within a certain power.

It should be noted that, in the description of the present invention, it should be understood that the above modules and components are for convenience of description and simplicity of description, and do not indicate or imply that the referred components or elements must have separate and independent physical structures, and the above modules and components may be actually separated into different physical modules, or a plurality of modules and components may be combined into one physical module, and thus, the present invention should not be construed as being limited.

The above-described embodiments are merely illustrative of the preferred embodiments of the present invention, and do not limit the scope of the present invention, and various changes, modifications, alterations, and substitutions which may be made by those skilled in the art without departing from the spirit of the present invention shall fall within the protection scope defined by the claims of the present invention.