CN112684238B - Switch power tube load current real-time monitoring circuit and monitoring system - Google Patents
Switch power tube load current real-time monitoring circuit and monitoring system Download PDFInfo
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Abstract
The invention discloses a real-time monitoring circuit and a monitoring system for load current of a switch power tube. The system comprises a digital power amplifier driving circuit, a half-bridge MOSFET circuit and a sampling output circuit, wherein the digital power amplifier driving circuit is connected with an audio signal and modulates the input audio signal; the half-bridge MOSFET circuit is used for converting a small-signal pulse square wave signal into a high-voltage pulse square wave signal with low output impedance so as to realize high-power output; and the high-voltage pulse square wave signal is restored into a high-voltage audio signal through a low-pass filter so as to realize high-power sound expansion; the sampling output circuit adopts the monitoring circuit. The invention has reasonable structure and low cost, and monitors the working current of the switching power tube in real time.
Description
Technical Field
The invention relates to the technical field of audio power amplifier electronics, in particular to a real-time monitoring circuit and a monitoring system for load current of a switching power tube.
Background
Because of the uncertainty of the load of the digital power amplifier, in order to protect it in a safe operating range, it is necessary to detect its operating current and protect it in case of overcurrent. The protection modes are various, and the effects of silencing the power amplifier, cutting off the output, closing the power supply and the like can be achieved. But on the premise of being built on accurate, rapid current detection.
The detection means currently being used by designers are a resistance sampling method, a current transformer method, and the like. The resistance sampling method needs to connect sampling resistors in series to an output loop, so that power consumption can be generated as long as signals are output, and heat accumulation is a potential safety hazard point in a product when the current is overlarge; if too small a resistance is used, this may also lead to a decrease in the accuracy of the subsequent stage, and this contradiction and the response problem of the subsequent stage sampling circuit are often pain points for the designer. The current transformer method measures current by electromagnetic induction, only the line alternating current can be measured, the rear end can reach a directly usable signal only by special treatment, and the current transformer is large in size and high in cost. Moreover, the current value of the final output signal is detected in all the above modes, and the current flowing in real time of the switching power tube is not directly reflected. Because the current of the switch power tube is not zero when the digital power amplifier is in no signal output, but has linear current related to the power supply voltage and the filter inductor, the current of the switch power tube is not directly monitored and protected in the above mode, and once the saturation inductance of the inductor is suddenly reduced, the current of the switch power tube is suddenly increased, and overcurrent cannot be monitored and protected. And the risk of direct connection faults of the digital power amplifier switch power tube cannot be guaranteed.
In conclusion, the existing switch power tube load current detection modes (a resistance sampling method, a current mutual inductance method and the like) have high cost, large volume and poor precision, and cannot directly reflect the real-time working current of the power tube.
Disclosure of Invention
The invention aims to provide a real-time monitoring circuit and a monitoring system for the load current of a switching power tube, which have the advantages of low cost, simplicity and clarity, real-time monitoring of the working current of the switching power tube and capability of obtaining the actual output current through filter processing.
The invention is realized by the following technical scheme:
the monitoring circuit comprises a sampling bias circuit and a signal output circuit, wherein the sampling bias circuit is connected with the signal output circuit, and the monitoring circuit is used as a sampling output circuit of the switching power tube to realize real-time detection of the load current of the switching power tube.
At present, the existing switch power load current detection modes (a resistance sampling method, a current mutual inductance method and the like) are adopted, the resistance sampling method needs to connect sampling resistors in series to an output loop, power consumption can be generated as long as signals are output, and when the current is overlarge, heat accumulation is also a potential safety hazard point in a product; if too small a resistance is used, this may also lead to a decrease in the accuracy of the subsequent stage, and this contradiction and the response problem of the subsequent stage sampling circuit are often pain points for the designer. The current transformer method measures current by electromagnetic induction, only the line alternating current can be measured, the rear end can reach a directly usable signal only by special treatment, and the current transformer is large in size and high in cost. Moreover, the current value of the final output signal is detected in all the above modes, and the current flowing in real time of the switching power tube is not directly reflected. Because the current of the switch power tube is not zero when the digital power amplifier is in no signal output, but has linear current related to the power supply voltage and the filter inductor, the current of the switch power tube is not directly monitored and protected in the above mode, and once the saturation inductance of the inductor is suddenly reduced, the current of the switch power tube is suddenly increased, and overcurrent cannot be monitored and protected. And the risk of direct connection faults of the digital power amplifier switch power tube cannot be guaranteed. In summary, the existing switch power load current detection modes (such as a resistance sampling method and a current mutual inductance method) have high cost, large volume and poor precision, and cannot directly reflect the real-time working current of the power tube.
The invention aims to solve the problems that the existing switch power load current detection modes (a resistance sampling method, a current mutual inductance method and the like) are high in cost, large in size and poor in precision, and cannot directly reflect the real-time working current of a power tube, and designs a switch power tube load current real-time monitoring circuit which comprises a sampling bias circuit and a signal output circuit, wherein the sampling bias circuit is connected with the signal output circuit, and the monitoring circuit is used as the sampling output circuit of the switch power tube to realize the real-time detection of the load current of the switch power tube; the invention has simple and reasonable structure, low cost, simplicity and clarity, monitors the working current of the switching power tube in real time, and can obtain the actual output current through the filter treatment.
As a further preferable scheme, the sampling bias circuit comprises a bias pull-up resistor R1 and a bias unidirectional diode D1, and the signal output circuit comprises an amplifying triode Q5, a base resistor Rb, a collector resistor Rc and an emitter resistor Re, wherein:
the positive electrode of the bias unidirectional diode D1 is connected with a base resistor Rb, the base resistor Rb is connected with the base electrode of the amplifying triode Q5, the collector electrode of the amplifying triode Q5 is connected with a collector resistor Rc, and the emitter electrode of the amplifying triode Q5 is connected with an emitter resistor Re; the negative electrode of the biased unidirectional diode D1 is connected with a switching power tube circuit; the collector resistor Rc is grounded;
One end of the bias pull-up resistor R1 is connected with the common end of the bias unidirectional diode D1 and the base resistor Rb, and the other end is connected with the switching power tube circuit.
As a further preferable mode, the amplifying triode Q5 is an NPN triode.
As a further preferable scheme, the voltage on the collector resistor Rc is used as the output voltage of the monitoring circuit to obtain voltage output of-5V to 0V for the later stage sampling of the switching power tube.
On the other hand, the invention also provides a real-time monitoring system for the load current of the switching power tube, which comprises a digital power amplifier driving circuit, a half-bridge MOSFET circuit and a sampling output circuit, wherein the digital power amplifier driving circuit is connected with the half-bridge MOSFET circuit, the half-bridge MOSFET circuit is connected with the sampling output circuit, and the sampling output circuit is also connected with a public end of the digital power amplifier driving circuit and the half-bridge MOSFET circuit;
The digital power amplifier driving circuit is connected with an audio signal and transmits the modulated signal to the half-bridge MOSFET circuit; the half-bridge MOSFET circuit is used for converting a small-signal pulse square wave signal into a high-voltage pulse square wave signal with low output impedance so as to realize high-power output; and the high-voltage pulse square wave signal is restored into a high-voltage audio signal through a low-pass filter so as to realize high-power sound expansion;
the sampling output circuit adopts the switch power tube load current real-time monitoring circuit.
As a further preferable scheme, the digital power amplifier driving circuit comprises a PWM modulator and a triode totem circuit, wherein the PWM modulator is connected with the triode totem circuit, and is connected with an audio signal and modulates the connected audio signal into pulse square wave signals with different duty ratios, and the pulse square wave signals are output through the triode totem circuit in a push-pull way.
As a further preferable scheme, the triode totem circuit comprises a triode Q1 and a triode Q2 which are complementary, wherein the base electrode of the triode Q1 is connected with the base electrode of the triode Q2, the collector electrode of the triode Q1 is connected with the positive electrode (VDD) of the driving power supply voltage, the emitter electrode of the triode Q1 is connected with the emitter electrode of the triode Q2, and the collector electrode of the triode Q2 is connected with the negative electrode (VEE) of the driving power supply voltage; and the common end of the emitter of the triode Q1 and the emitter of the triode Q2 is connected with the half-bridge MOSFET circuit.
As a further preferable scheme, the half-bridge MOSFET circuit includes a MOS transistor Q3 and a MOS transistor Q4, a drain electrode of the transistor Q1 is connected to a positive electrode (VCC) of a power supply voltage, a source electrode of the transistor Q1 is connected to a source electrode of the transistor Q2, a drain electrode of the transistor Q2 is connected to a negative electrode (VEE) of the power supply voltage, and a gate electrode of the transistor Q2 is connected to an output end of the digital power amplifier driving circuit through a resistor R2;
The common terminal of the source electrode of the triode Q1 and the source electrode of the triode Q2 is connected with the switch power tube load current real-time monitoring circuit (namely, the common terminal of the source electrode of the triode Q1 and the source electrode of the triode Q2 is connected with the cathode of the bias unidirectional diode D1).
As a further preferable scheme, the filter further comprises a low-pass filter LC, wherein the low-pass filter LC comprises an inductor L1 and a capacitor C1; one end of the inductor L1 is connected with the common end of the MOS tube Q3 and the common end of the MOS tube Q4, and the other end of the inductor L1 is connected with a voltage output end; the common terminal of the inductor L1 and the voltage output terminal is connected with one end of the capacitor C1, and the other end of the capacitor C1 is grounded.
As a further preferable scheme, the MOS tube Q3 and the MOS tube Q4 are both N-channel MOSFETs.
Compared with the prior art, the invention has the following advantages and beneficial effects:
1. the invention detects current in real time by using the driving voltage, and the detection circuit can output an effective voltage value only when the power switch tube is turned on.
2. The invention obtains the current value passing through the MOSFET in real time by utilizing the self-conduction resistance characteristic of the MOSFET.
3. The current detected by the invention is not only the current on the digital power amplifier load, but also the current actually and truly flows at any moment when the power switch tube is conducted (including the current flowing through the switch tube when the digital power amplifier is in idle load).
4. The invention designs a real-time monitoring circuit for the load current of a switching power tube, which comprises a sampling bias circuit and a signal output circuit, wherein the sampling bias circuit is connected with the signal output circuit, and the monitoring circuit is used as the sampling output circuit of the switching power tube to realize the real-time detection of the load current of the switching power tube; the invention has simple and reasonable structure, low cost, simplicity and clarity, monitors the working current of the switching power tube in real time, and can obtain the actual output current through the filter treatment.
Drawings
The accompanying drawings, which are included to provide a further understanding of embodiments of the application and are incorporated in and constitute a part of this specification, illustrate embodiments of the application and together with the description serve to explain the principles of the application. In the drawings:
Fig. 1 is a circuit diagram of a real-time monitoring circuit and a monitoring system for load current of a switching power tube according to the present invention.
Detailed Description
For the purpose of making apparent the objects, technical solutions and advantages of the present invention, the present invention will be further described in detail with reference to the following examples and the accompanying drawings, wherein the exemplary embodiments of the present invention and the descriptions thereof are for illustrating the present invention only and are not to be construed as limiting the present invention.
In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be apparent to one of ordinary skill in the art that: no such specific details are necessary to practice the invention. In other instances, well-known structures, circuits, materials, or methods have not been described in detail in order not to obscure the invention.
Throughout the specification, references to "one embodiment," "an embodiment," "one example," or "an example" mean: a particular feature, structure, or characteristic described in connection with the embodiment or example is included within at least one embodiment of the invention. Thus, the appearances of the phrases "in one embodiment," "in an example," or "in an example" in various places throughout this specification are not necessarily all referring to the same embodiment or example. Furthermore, the particular features, structures, or characteristics may be combined in any suitable combination and/or sub-combination in one or more embodiments or examples. Moreover, those of ordinary skill in the art will appreciate that the illustrations provided herein are for illustrative purposes and that the illustrations are not necessarily drawn to scale. The term "and/or" as used herein includes any and all combinations of one or more of the associated listed items.
In the description of the present invention, the terms "front", "rear", "left", "right", "upper", "lower", "vertical", "horizontal", "high", "low", "inner", "outer", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, merely to facilitate description of the present invention and simplify description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be configured and operated in a specific orientation, and therefore should not be construed as limiting the scope of the present invention.
Examples
As shown in fig. 1, the switch power tube load current real-time monitoring circuit comprises a sampling bias circuit and a signal output circuit, wherein the sampling bias circuit is connected with the signal output circuit, and the monitoring circuit is used as the sampling output circuit of the switch power tube to realize real-time detection of the switch power tube load current.
The invention relates to a real-time monitoring circuit for load current of a switching power tube, which is a circuit for determining the current passing through the power tube MOSFET through the self-characteristics of the power tube MOSFET, is very practical and accurate, and is known to have an m omega-level on-resistance Rds (on) after the power tube MOSFET is completely conducted, when current Id passes through the MOSFET, a tube voltage drop Vd=Id x Rds (on) is formed on the on-resistance, and the Vd can be used as a circuit for detecting the current flowing through the MOSFET in real time, so that the invention is a circuit for detecting the Vd (load current Id).
Specifically, the sampling bias circuit comprises a bias pull-up resistor R1 and a bias unidirectional diode D1, and the signal output circuit comprises an amplifying triode Q5, a base resistor Rb, a collector resistor Rc and an emitter resistor Re, wherein:
the positive electrode of the bias unidirectional diode D1 is connected with a base resistor Rb, the base resistor Rb is connected with the base electrode of the amplifying triode Q5, the collector electrode of the amplifying triode Q5 is connected with a collector resistor Rc, and the emitter electrode of the amplifying triode Q5 is connected with an emitter resistor Re; the negative electrode of the biased unidirectional diode D1 is connected with a switching power tube circuit; the collector resistor Rc is grounded;
One end of the bias pull-up resistor R1 is connected with the common end of the bias unidirectional diode D1 and the base resistor Rb, and the other end is connected with the switching power tube circuit.
Specifically, the amplifying triode Q5 adopts an NPN triode.
Specifically, the voltage on the collector resistor Rc is used as the output voltage of the monitoring circuit to obtain voltage output of-5V to 0V for the later stage sampling of the switching power tube.
The invention aims to solve the problems that the existing switch power load current detection modes (a resistance sampling method, a current mutual inductance method and the like) are high in cost, large in size and poor in precision, and cannot directly reflect the real-time working current of a power tube, and designs a switch power tube load current real-time monitoring circuit which comprises a sampling bias circuit and a signal output circuit, wherein the sampling bias circuit is connected with the signal output circuit, and the monitoring circuit is used as the sampling output circuit of the switch power tube to realize the real-time detection of the load current of the switch power tube; the invention has simple and reasonable structure, low cost, simplicity and clarity, monitors the working current of the switching power tube in real time, and can obtain the actual output current through the filter treatment.
Example 2
As shown in fig. 1, the difference between the present embodiment and embodiment 1 is that the present embodiment provides a real-time monitoring system for load current of a switching power tube, the system includes a digital power amplifier driving circuit, a half-bridge MOSFET circuit, and a sampling output circuit, the digital power amplifier driving circuit is connected to the half-bridge MOSFET circuit, the half-bridge MOSFET circuit is connected to the sampling output circuit, and the sampling output circuit is further connected to a common end of the digital power amplifier driving circuit and the half-bridge MOSFET circuit;
The digital power amplifier driving circuit is connected with an audio signal and transmits the modulated signal to the half-bridge MOSFET circuit; the half-bridge MOSFET circuit is used for converting a small-signal pulse square wave signal into a high-voltage pulse square wave signal with low output impedance so as to realize high-power output; and the high-voltage pulse square wave signal is restored into a high-voltage audio signal through a low-pass filter so as to realize high-power sound expansion;
the sampling output circuit adopts the switch power tube load current real-time monitoring circuit.
Specifically, the digital power amplifier driving circuit comprises a PWM modulator and a triode totem circuit, wherein the PWM modulator is connected with the triode totem circuit, the PWM modulator is connected with an audio signal and modulates the connected audio signal into pulse square wave signals with different duty ratios, and the pulse square wave signals are output through the triode totem circuit in a push-pull way.
Specifically, the triode totem circuit comprises a triode Q1 and a triode Q2 which are complementary, wherein the base electrode of the triode Q1 is connected with the base electrode of the triode Q2, the collector electrode of the triode Q1 is connected with the positive electrode (VDD) of the driving power supply voltage, the emitter electrode of the triode Q1 is connected with the emitter electrode of the triode Q2, and the collector electrode of the triode Q2 is connected with the negative electrode (VEE) of the driving power supply voltage; and the common end of the emitter of the triode Q1 and the emitter of the triode Q2 is connected with the half-bridge MOSFET circuit.
Specifically, the half-bridge MOSFET circuit includes a MOS transistor Q3 and a MOS transistor Q4, a drain electrode of the transistor Q1 is connected to a positive electrode (VCC) of a supply voltage, a source electrode of the transistor Q1 is connected to a source electrode of the transistor Q2, a drain electrode of the transistor Q2 is connected to a negative electrode (VEE) of the supply voltage, and a gate electrode of the transistor Q2 is connected to an output end of the digital power amplifier driving circuit through a resistor R2;
The common terminal of the source electrode of the triode Q1 and the source electrode of the triode Q2 is connected with the switch power tube load current real-time monitoring circuit (namely, the common terminal of the source electrode of the triode Q1 and the source electrode of the triode Q2 is connected with the cathode of the bias unidirectional diode D1).
Specifically, the low-pass filter LC includes an inductance L1 and a capacitance C1; one end of the inductor L1 is connected with the common end of the MOS tube Q3 and the common end of the MOS tube Q4, and the other end of the inductor L1 is connected with a voltage output end; the common terminal of the inductor L1 and the voltage output terminal is connected with one end of the capacitor C1, and the other end of the capacitor C1 is grounded.
Specifically, the MOS transistor Q3 and the MOS transistor Q4 are N-channel MOSFETs.
The implementation process comprises the following steps: as shown in fig. 1, the whole system comprises a digital power amplifier driving circuit, a half-bridge MOSFET circuit and a sampling output circuit; the digital power amplifier driving circuit is a pulse square wave signal (PWM modulator in figure 1) which modulates an audio signal into different duty ratios, and then a triode totem circuit (Q1 and Q2 complementary triodes in figure 1) is used for push-pull output; the half-bridge MOSFET circuit is used for converting a small-signal pulse square wave signal (Q3 and Q4N channel MOSFET half-bridge in FIG. 1) into a high-voltage pulse square wave signal with very low output impedance so as to realize high-power output; and finally, restoring the high-voltage pulse square wave signal into a high-voltage audio signal through an LC low-pass filter so as to realize high-power sound expansion.
The invention relates to a real-time monitoring circuit for load current of a switching power tube, which consists of a sampling output circuit in a dotted line frame in fig. 1; the sampling output circuit comprises a sampling bias circuit and a signal output circuit;
The sampling bias circuit comprises a bias pull-up resistor R1 and a bias unidirectional diode D1, wherein the bias pull-up resistor R1, the bias unidirectional diode D1 and the MOS tube Q4 (namely the power switch tube Q4) jointly form a sampling loop, namely a resistor Rds (on) when the R1, the D1 and the Q4 are conducted, the sampling loop only works when the driving circuit outputs a high level (is cut off when the driving circuit outputs a low level), namely the MOS tube Q4 (namely the power switch tube Q4) works when the MOS tube Q4 is conducted, and the real property and the stability are further reflected. When the driving signal drives the output high driving Q4, the sampling circuit a-B-C-D is formed, the on-state resistor voltage drop of the MOS transistor Q4 and the bias diode D1 clamp the voltage at the point B in fig. 1, and the voltage VB at the point B varies along with the variation of the current Id flowing through the MOS transistor Q4 (i.e., the power switch transistor Q4).
The signal output circuit is a common emitter triode amplifying circuit and comprises an amplifying triode Q5, a base resistor Rb, a collector resistor Rc and an emitter resistor Re; in FIG. 1, the sampling voltage VB at the point B is based on a VEE power rail, and a digital power amplifier generally has the absolute value voltage of VEE as high as-100V or even higher and is difficult to use by a later-stage circuit, so that the amplifying circuit has the functions of amplifying voltage and current and level reference lifting and shifting; in the fig. 1, the transistor Q5 realizes the current amplification function, and under the action of the base resistor Rb and the emitter resistor Re, the base current IRb output to the transistor Q5 by the sampling bias circuit can be as small as possible, so that the influence on the driving of the power switch tube is reduced; the current amplified by the triode Q5 is converted into voltage by the collector resistor Rc, one end of the collector resistor Rc is grounded (0V), so that the voltage on the collector resistor Rc is the final output voltage of the invention, namely the load current I-OUT is converted into the output value of the voltage, the voltage is negative voltage with 0V level as a reference, and the voltage output of-5V to 0V can be obtained through strict value taking, thereby being convenient for later sampling.
Working principle analysis:
sampling bias circuit: setting the driving power supply voltage as VDD; biasing the forward voltage of the unidirectional diode D1 to Vd;
when the triode Q1 (used as a driving tube) is conducted, the voltage at the point A is VDD, the MOS tube Q4 (namely the power switch tube Q4) works normally, and the sampling bias circuit works; the point A voltage applies source energy to the bias sampling loop through the bias pull-up resistor R1, so that the loop is conducted in the forward direction. B will generate a voltage related to the on-resistance Rds (on) of the MOS transistor Q4 (i.e. the power switch transistor Q4) and the load current.
Neglecting the influence of the base current IRb of the transistor Q5 of the signal output circuit on the sampling loop, wherein the B-point voltage vb=rds (on) id+vd;
a signal output circuit: setting the direct current amplification factor of the triode Q5 as beta, and setting the starting voltage of the B-E electrode as Vbe;
at this time, the voltage at the point B is directly output by the triode Q5, obtained according to the common emitter amplifying circuit,
The transistor Q5 is input into the loop,
VB＝IRb*Rb+Vbe+(β+1)*IRb*Re；
The collector of the triode Q5 outputs a voltage,
VP＝-β*IRb*Rc；
An output voltage is finally obtained which is related to the load current,
Thus, an expression of VP and Id is shown, the real-time load current Id required by the invention is shown by VP, and the circuit is simple and reliable.
The invention utilizes the driving voltage to detect the current in real time, and the detection circuit can output an effective voltage value only when the power switch tube is conducted; the invention utilizes the self-conduction resistance characteristic of the MOSFET to obtain the current value passing through the MOSFET in real time; the current detected by the invention is not only the current on the digital power amplifier load, but also the current actually and truly flows at any moment when the power switch tube is conducted (including the current flowing through the switch tube when the digital power amplifier is in idle load).
The foregoing description of the embodiments has been provided for the purpose of illustrating the general principles of the invention, and is not meant to limit the scope of the invention, but to limit the invention to the particular embodiments, and any modifications, equivalents, improvements, etc. that fall within the spirit and principles of the invention are intended to be included within the scope of the invention.
Claims (9)
1. The real-time monitoring circuit for the load current of the switching power tube is characterized by comprising a sampling bias circuit and a signal output circuit, wherein the sampling bias circuit is connected with the signal output circuit, and the monitoring circuit is used as the sampling output circuit of the switching power tube to realize real-time detection of the load current of the switching power tube;
The sampling bias circuit comprises a bias pull-up resistor R1 and a bias unidirectional diode D1, and the signal output circuit comprises an amplifying triode Q5, a base resistor Rb, a collector resistor Rc and an emitter resistor Re, wherein:
the positive electrode of the bias unidirectional diode D1 is connected with a base resistor Rb, the base resistor Rb is connected with the base electrode of the amplifying triode Q5, the collector electrode of the amplifying triode Q5 is connected with a collector resistor Rc, and the emitter electrode of the amplifying triode Q5 is connected with an emitter resistor Re; the negative electrode of the biased unidirectional diode D1 is connected with a switching power tube circuit; the collector resistor Rc is grounded;
One end of the bias pull-up resistor R1 is connected with the common end of the bias unidirectional diode D1 and the base resistor Rb, and the other end is connected with the switching power tube circuit.
2. The real-time monitoring circuit of switching power tube load current according to claim 1, wherein the amplifying triode Q5 is an NPN triode.
3. The real-time monitoring circuit for the load current of the switching power tube according to claim 1, wherein the voltage on the collector resistor Rc is used as the output voltage of the monitoring circuit to obtain the voltage output of-5V to 0V for the later stage sampling of the switching power tube.
4. The real-time monitoring system for the load current of the switching power tube is characterized by comprising a digital power amplifier driving circuit, a half-bridge MOSFET circuit and a sampling output circuit, wherein the digital power amplifier driving circuit is connected with the half-bridge MOSFET circuit, the half-bridge MOSFET circuit is connected with the sampling output circuit, and the sampling output circuit is also connected with a common end of the digital power amplifier driving circuit and the half-bridge MOSFET circuit;
The digital power amplifier driving circuit is connected with an audio signal and transmits the modulated signal to the half-bridge MOSFET circuit; the half-bridge MOSFET circuit is used for converting a small-signal pulse square wave signal into a high-voltage pulse square wave signal with low output impedance so as to realize high-power output; and the high-voltage pulse square wave signal is restored into a high-voltage audio signal through a low-pass filter so as to realize high-power sound expansion;
The sampling output circuit adopts the switching power tube load current real-time monitoring circuit as claimed in any one of claims 1 to 3.
5. The real-time monitoring system for load current of switching power tube according to claim 4, wherein the digital power amplifier driving circuit comprises a PWM modulator and a triode totem circuit, the PWM modulator is connected with the triode totem circuit, the PWM modulator is connected with an audio signal and modulates the connected audio signal into pulse square wave signals with different duty ratios, and the pulse square wave signals are output in a push-pull way through the triode totem circuit.
6. The real-time monitoring system of switching power tube load current according to claim 5, wherein the triode totem circuit comprises a complementary triode Q1 and triode Q2, wherein the base electrode of the triode Q1 is connected with the base electrode of the triode Q2, the collector electrode of the triode Q1 is connected with the positive electrode of the driving power supply voltage, the emitter electrode of the triode Q1 is connected with the emitter electrode of the triode Q2, and the collector electrode of the triode Q2 is connected with the negative electrode of the driving power supply voltage; and the common end of the emitter of the triode Q1 and the emitter of the triode Q2 is connected with the half-bridge MOSFET circuit.
7. The real-time monitoring system for the load current of the switching power tube according to claim 4, wherein the half-bridge MOSFET circuit comprises a MOS tube Q3 and a MOS tube Q4, a drain electrode of the triode Q1 is connected with a positive electrode of a power supply voltage, a source electrode of the triode Q1 is connected with a source electrode of a triode Q2, a drain electrode of the triode Q2 is connected with a negative electrode of the power supply voltage, and a grid electrode of the triode Q2 is connected with an output end of the digital power amplifier driving circuit through a resistor R2;
the common terminal of the source electrode of the triode Q1 and the source electrode of the triode Q2 is connected with the sampling output circuit.
8. The real-time monitoring system of switching power tube load current according to claim 7, further comprising a low-pass filter LC, wherein the low-pass filter LC comprises an inductance L1 and a capacitance C1; one end of the inductor L1 is connected with the common end of the MOS tube Q3 and the common end of the MOS tube Q4, and the other end of the inductor L1 is connected with a voltage output end; the common terminal of the inductor L1 and the voltage output terminal is connected with one end of the capacitor C1, and the other end of the capacitor C1 is grounded.
9. The real-time monitoring system for load current of switching power tube according to claim 7, wherein the MOS tube Q3 and the MOS tube Q4 are N-channel MOSFETs.
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| CN202110023132.6A CN112684238B (en) | 2021-01-08 | 2021-01-08 | Switch power tube load current real-time monitoring circuit and monitoring system |
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| CN113791266A (en) * | 2021-10-09 | 2021-12-14 | 富芯微电子有限公司 | MOSFET current detection device |
| CN113984244B (en) * | 2021-10-22 | 2023-10-20 | 臻驱科技（上海）有限公司 | Protection circuit of motor temperature sampling interface, motor temperature sampling module and electric vehicle |
| CN114487554B (en) * | 2022-01-28 | 2024-05-14 | 西北核技术研究所 | IV measuring method of pulse power amplifier |
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