A full-wave rectifier circuit

Abstract

The application relates to the field of electronic circuits, and discloses a full-wave rectifier circuit which comprises a first operational amplifier, a second operational amplifier, an inductor coil, a resistor and a detection device, wherein the same polarity supply terminals of the first operational amplifier and the second operational amplifier are connected in parallel, one end of the inductor coil is connected to the output end of the first operational amplifier, the other end of the inductor coil is connected to the output end of the second operational amplifier, the power supply supplies power to the first operational amplifier and the second operational amplifier through the resistor, the detection port of the detection device is connected in parallel with the first resistor, and a full-wave rectification signal is output by the detection device. The full-wave rectifier circuit has simple circuit, does not need to use a diode for rectification, can accurately control the threshold value of the rectifier circuit, effectively detects the direct-current leakage current, effectively detects the high-frequency high-order harmonic leakage current which has potential harm, and has low cost.

Description

Technical Field

[0001] This invention relates to the field of electronic circuits, and more particularly to a full-wave rectifier circuit for small-signal processing. Background Technology

[0002] Put the right The conversion of a negative alternating voltage into a unipolar voltage is called rectification. Full-wave rectifier circuits generally refer to two types: one is used in DC power supplies, such as... Figure 1-1 As shown, Figure 1-1 This is a full-wave rectifier and filter circuit, which generally cannot be used directly for mains power rectification. It usually needs to pass through the center tap winding of the secondary side of transformer B1 to obtain two sets of identical voltages. Only voltages U1 and U2 with opposite phases can be used; Figure 1-2 It is a bridge rectifier circuit in a full-wave rectifier circuit, also called a full-bridge rectifier circuit. If capacitor C L When not connected, its output waveform is pulsating DC, which is the load R. L The waveform on the screen; capacitor C L After connection, its output waveform is a relatively smooth pulsating DC current.

[0003] Another type of circuit is used in voltage signal processing circuits. The book *Fundamentals of Analog Electronics*, published in 1988, edited by Tong Shibai, ISBN 7-04-000868-8 / TN•53, shows a full-wave precision rectifier circuit in Figure 9-31 on page 575. This original figure is cited herein as an example. Figure 1-3 The rectifier circuit consists of two parts: a half-wave precision rectifier circuit and an inverting summing circuit. This circuit has an inverting input and low input impedance. To address the low input impedance, Figure 9-32 on page 576 of the book shows a full-wave precision rectifier circuit with high input impedance; this figure is cited here as the basis for this application. Figure 1-4

[0004] Figure 1-3 and Figure 1-4 The circuit uses two operational amplifiers for full-wave precision rectification. Operational amplifier A1 forms a half-wave precision rectifier circuit, and operational amplifier A2 forms a summing circuit. The circuit configuration is complex, and diodes are used in the external circuitry of operational amplifier A1 to implement full-wave rectification circuits at the signal level.

[0005] In addition, some protection circuits also use similar rectifier circuits used in DC power supplies, such as the DRV411 integrated circuit produced by Texas Instruments. Figures 56 and 57 in the 2013 datasheet of this circuit show this circuit. Figure 56 is referenced here for this application. Figure 1-5 As can be seen, diode D1 D2 D3 D4 forms a protection circuit identical to the full-wave rectifier circuit, and it does indeed operate in full-wave rectification mode when the compensation coil is overloaded.

[0006] Currently, with the reduction in cost, improvement in efficiency, and enhanced reliability of switching power supplies, DC power supply has become a trend. Previously, DC power supply was not widely adopted due to its inability to solve a series of problems, such as long-distance transmission, making AC power supply the core of industry. At present, DC power supply appears to be the most cost-effective option. Low operating costs, no power factor compensation Grid connection is extremely easy, and underground Submarine power generation is easier to implement and facilitates distributed solar power generation for individual households, and may become the mainstream in the future. However, leakage protection remains a challenge when using DC power.

[0007] DC-powered residual current devices (RCDs) differ from AC-powered RCDs. AC RCDs typically operate as follows: the live wire and neutral wire pass through a toroidal core with high permeability; early versions also used iron cores. In a residual current device (RCD), the live wire and neutral wire are considered as a parallel line. If there is a leakage current, there will be a current difference between the live wire and the neutral wire, and the current in the parallel line will no longer be zero. This current still has the same frequency as the mains current. An induction coil with 1000 to 3000 turns is wound on a toroidal core. The induction coil induces a voltage, which is essentially a voltage formed across a large-resistance load resistor by a weak induced current. This voltage drives the control section to quickly cut off the switch (trip). The leakage current protection threshold is usually 20-30mA. A transformer is composed of a toroidal magnetic core with high permeability, an induction coil, and the parallel connection of the live and neutral wires.

[0008] The circuit of the AC leakage current protector described above cannot be used to design a leakage current protector for a DC power supply system because DC current cannot be directly transmitted through a transformer. In other words, the DC leakage current cannot be directly detected using a transformer through the aforementioned technical solution.

[0009] DC residual current devices (RCDs) typically employ fluxgate current sensors in conjunction with a control unit to trip the circuit when the leakage current exceeds a threshold. This results in a significantly more complex circuit. While the market expectation is that the cost of DC RCDs should not exceed that of AC RCDs, the current cost of DC RCDs remains higher than that of AC RCDs, and their static power consumption is also far greater.

[0010] The full-wave rectifier circuit in the fluxgate current sensor also contributes to the cost. Traditional circuits are complex and contain many components; consequently, with the same components, the quiescent operating current is also larger. Summary of the Invention

[0011] In view of this, the technical problem to be solved by the present invention is to provide a full-wave rectifier circuit that is simple in design, does not use diodes for rectification, and can control the threshold voltage of the rectifier circuit more precisely.

[0012] The technical solution of the present invention to solve the above-mentioned technical problems is as follows:

[0013] A full-wave rectifier circuit, comprising: a first operational amplifier The system comprises a second operational amplifier, an inductor, resistors, and a detection device. The same-polarity power supply terminals of the first and second operational amplifiers are connected in parallel. The output terminal of the first operational amplifier is connected to one end of the inductor, and the other end of the inductor is connected to the output terminal of the second operational amplifier. Resistors are connected to the power supply terminals of both the first and second operational amplifiers, and the power supply is provided to both operational amplifiers through these resistors. The detection port of the detection device is connected in parallel with the resistors, and the detection device is used to output a full-wave rectified signal.

[0014] Preferably, the input terminal of the first operational amplifier is used to connect to the input voltage signal; the input terminal of the second operational amplifier is used to connect to the reference voltage source.

[0015] Preferably, the first end of the resistor is used to connect to the power supply, and the second end of the resistor is connected to the power supply terminals of the first operational amplifier and the second operational amplifier, respectively.

[0016] Preferably, the detection device is a transistor, with the emitter and base of the transistor serving as detection ports. The emitter of the transistor is connected to the first end of the resistor, and the base of the transistor is connected to the second end of the resistor.

[0017] Preferably, the detection device is an operational amplifier, with the inverting input terminal and the power supply terminal of the operational amplifier serving as detection ports. The inverting input terminal of the operational amplifier is connected to the second end of the resistor, and the power supply terminal of the operational amplifier is connected to the first end of the resistor.

[0018] Preferably, the detection device is a comparator, with the inverting input terminal and the power supply terminal of the comparator serving as detection ports. The inverting input terminal of the comparator is connected to the second terminal of the resistor, and the power supply terminal of the comparator is connected to the first terminal of the resistor.

[0019] The present invention also provides a full-wave rectifier circuit, comprising: a first operational amplifier. The system comprises a second operational amplifier, an inductor, a constant current source, and a detection device. The same-polarity power supply terminals of the first and second operational amplifiers are connected in parallel. The output terminal of the first operational amplifier is connected to one end of the inductor, and the other end of the inductor is connected to the output terminal of the second operational amplifier. The constant current source is connected to the power supply terminals of both the first and second operational amplifiers, and the power supply provides power to both operational amplifiers through the constant current source. The detection port of the detection device is connected in parallel with the constant current source, and the detection device is used to output a full-wave rectified signal.

[0020] Preferably, the first end of the constant current source is used to connect to the power supply, and the second end of the constant current source is connected to the power supply terminal of the first operational amplifier and the power supply terminal of the second operational amplifier, respectively.

[0021] Preferably, the detection device is a transistor, with the emitter and base of the transistor serving as detection ports. The emitter of the transistor is connected to the first end of the constant current source, and the base of the transistor is connected to the second end of the constant current source.

[0022] Preferably, the detection device is an operational amplifier or comparator, with the inverting input terminal and power supply terminal of the operational amplifier or comparator serving as detection ports. The inverting input terminal of the operational amplifier or comparator is connected to the second terminal of the constant current source, and the power supply terminal of the operational amplifier or comparator is connected to the first terminal of the constant current source.

[0023] Preferably, the current of the constant current source is above the total current, which is the sum of the quiescent operating current of the first operational amplifier, the quiescent operating current of the second operational amplifier, and the leakage current threshold divided by the number of turns of the inductor coil.

[0024] The beneficial effects of the full-wave rectifier circuit of this invention are as follows:

[0025] The full-wave rectifier circuit of this invention is simple in design, eliminates the need for rectifier diodes, and can precisely control the threshold of the rectifier circuit. It not only effectively detects DC leakage current but also effectively detects potentially hazardous high-frequency high-order harmonic leakage currents, and is low in cost. Attached Figure Description

[0026] Figure 1-1 This is a diagram of an existing full-wave rectifier circuit used in DC power supplies.

[0027] Figure 1-2 This is a diagram of an existing bridge rectifier circuit used in DC power supplies.

[0028] Figure 1-3 The circuit diagram shows a full-wave precision rectifier circuit composed of two operational amplifiers.

[0029] Figure 1-4 The circuit diagram shows a high-input-resistance full-wave precision rectifier circuit composed of two operational amplifiers.

[0030] Figure 1-5 The circuit diagram shows the protection circuit currently operating in full-wave rectification mode.

[0031] Figure 2 This is a schematic diagram of the full-wave rectifier circuit according to the first embodiment of the present invention;

[0032] Figure 3 This is a schematic diagram of the full-wave rectifier circuit according to the second embodiment of the present invention;

[0033] Figures 4-1 to 4-7 This is a schematic diagram of the constant current source in the full-wave rectifier circuit of the second embodiment of the present invention;

[0034] Figure 5 This is a schematic diagram of the full-wave rectifier circuit according to the third embodiment of the present invention;

[0035] Figure 5-1 Schematic diagram of a constant current source to replace resistor R;

[0036] Figure 6 This is a schematic diagram of the full-wave rectifier circuit according to the fourth embodiment of the present invention;

[0037] Figure 7 This is a schematic diagram of the full-wave rectifier circuit according to the fifth embodiment of the present invention. Detailed Implementation

[0038] To enable those skilled in the art to more readily understand the present invention, the present invention will be described below in conjunction with specific embodiments.

[0039] First Embodiment

[0040] Please see Figure 2 , Figure 2 This is a schematic diagram of a full-wave rectifier circuit according to the first embodiment of the present invention, used for small signal processing. The full-wave rectifier circuit in this embodiment includes: a first operational amplifier A1 Second op-amp A2 Inductor L Resistor R and sensing device Q The input terminal of the first operational amplifier A1 is connected to the input voltage signal, and the output terminal of the first operational amplifier A1 is connected to one end of the inductor L. The positive power supply terminal a+ of the first operational amplifier is connected to the positive power supply terminal b+ of the second operational amplifier A2, and the negative power supply terminal a- of the first operational amplifier and the negative power supply terminal b- of the second operational amplifier A2 are connected. This method is simply referred to as: the power supply terminals of the first and second operational amplifiers with the same polarity are connected in parallel. The input terminal of the second operational amplifier A2 is connected to the reference voltage source, and the output terminal of the second operational amplifier A2 is connected to the other end of the inductor L. The negative power supply terminal b- of the second operational amplifier A2 is connected to the negative power supply VEE or ground. The first end of the resistor R is connected to the power supply V. CC The second end of resistor R is connected to the positive power supply terminal a+ of the first operational amplifier A1 and the positive power supply terminal b+ of the second operational amplifier A2. The power supply V... CC The first operational amplifier A1 and the second operational amplifier A2 are powered through resistor R; the two detection ports of the detection device Q are connected in parallel across resistor R. In this embodiment, the detection device Q is a transistor Q, specifically a PNP transistor. The emitter and base of transistor Q serve as detection ports. The emitter of transistor Q is connected to the first end of resistor R, and the base of transistor Q is connected to the second end of resistor R. The collector of transistor Q is used to output the full-wave rectified signal obtained by full-wave rectification of the input voltage signal.

[0041] The working principle of the full-wave rectifier circuit in this embodiment is as follows:

[0042] The first operational amplifier A1, hereinafter referred to as operational amplifier A1 in this embodiment; the second operational amplifier A2, hereinafter referred to as operational amplifier A2 in this embodiment. To facilitate understanding of its working principle, the application of this invention in a DC leakage current protector is used as an example for explanation. The input terminal of operational amplifier A1 is connected to the input voltage signal, specifically to the output terminal of the phase detector that forms the fluxgate in the DC leakage current protector. When the non-inverting input terminal of operational amplifier A2 is connected to a reference voltage source, operational amplifier A2 forms a voltage follower, artificially dividing the single voltage into two voltages. The voltage of the reference voltage source can be any voltage value between the voltage of the positive power supply terminal a+ and the voltage of the negative power supply terminal a-. Commonly, when the negative power supply terminal a- is grounded, i.e., when operating with a single voltage, the reference voltage of the reference voltage source is 2.5V or 1.25V. If the negative power supply terminal a- is a negative voltage symmetrical to the positive power supply terminal a+, the reference voltage source is generally 0V, i.e., the same voltage as ground (GND). In this case, operational amplifier A2 can be omitted. Figure 2 The right end of the inductor L can be directly grounded. This allows op-amp A2 to output a constant DC voltage. Of course, op-amp A2 can also operate in a mode that amplifies inversely to op-amp A1. In this case, op-amp A1 and op-amp A2 are essentially operating in BTL mode. BTL is an abbreviation for Balanced Transformer Less, referring to BTL power amplifiers, commonly found in audio power amplifiers. When op-amps A1 and A2 operate in BTL mode, they allow the inductor coil L to be wound with finer enameled wire, or with twice the number of turns of the same enameled wire, to suit different applications.

[0043] When a DC leakage current occurs, the phase detector of the fluxgate outputs a differential voltage. This differential voltage is used as an input voltage signal to the input terminal of operational amplifier A1. This input voltage signal is amplified by operational amplifier A1, generating a current in the inductor L. The inductor L is a coil with a fixed number of turns, and the magnetic flux it generates is opposite to the magnetic flux generated by the parallel line of the DC power supply when leakage occurs. If the gain of operational amplifier A1 is high enough, the following equation appears after the entire circuit is in closed-loop operation:

[0044] ……………………Formula (1)

[0045] Where, leakage current is the differential current in the parallel line of DC power supply, n is the number of turns of inductor L, and I L The current in the inductor L This formula is derived from the Ampere-Zehnder law, which states that the parallel line of the DC power supply is considered as one turn. The magnetic flux it produces is largely canceled out by the reverse magnetic flux produced by the n turns of the inductor L. The remaining magnetic flux is detected by the phase detector circuit of the fluxgate, and the output is a difference voltage proportional to the remaining magnetic flux. This voltage is extremely weak, and after being amplified in open loop by operational amplifier A1, it generates a current I in the inductor L. L The product of this current and the number of turns n is the n×I in the above formula. L That is, the current I in the inductor L L It is always equal to the leakage current divided by the number of turns of the inductor L.

[0046] From the above analysis, it can be seen that I was measured. L This will reveal the magnitude of the leakage current. If you want to improve the efficiency of I... L To improve measurement accuracy, simply increase the open-loop gain of op-amp A1. However, if the open-loop gain of op-amp A1 is too high, the circuit is prone to self-oscillation, leading to the loss of its inherent function. Conversely, if a leakage current threshold is set, dividing it by the number of turns of the inductor L gives the current I in the inductor L. L threshold

[0047] Traditional detection of current I in inductor L L The method involves connecting a low-resistance, high-precision resistor (referred to as the sampling resistor) in series between the inductor L and the operational amplifier A2. By measuring the voltage across this resistor, the current I in the inductor L can be determined. L If the current exceeds a certain value, i.e., the voltage across the sensing resistor exceeds a certain value, other circuits will trip the DC leakage current protector's switch or relay, cutting off the power supply and protecting the user's safety. Detecting the voltage across the sampling resistor requires an operational amplifier or comparator, as well as a relatively precise rectifier circuit, making the circuit quite complex.

[0048] Next, the principle of the invention will be explained. If the current I in the inductor L... L The current flows from left to right, so op-amp A1 outputs current, while op-amp A2 outputs current flowing into it. Absorbing current Power supply V CC The supply current flows through resistor R, into the positive power supply terminal a+ of operational amplifier A1, and out from the output terminal of operational amplifier A1. Simultaneously, it flows into one end of inductor L (the left end), out from the right end of inductor L, and into the output terminal of operational amplifier A2. It then flows out from the negative power supply terminal b- of operational amplifier A2 and returns to the negative power supply V. EE , forming a loop Power supply V CC Equivalent to the positive terminal of a battery, and the negative power source V EE Equivalent to the negative terminal of a battery

[0049] At this time, the current flowing through resistor R is from top to bottom;

[0050] If the current I in the inductor L L The current flows from right to left, so op-amp A2 outputs current, while the output of op-amp A1 receives current flowing in. Absorbing current Power supply V CC The supply current flows through resistor R, into the positive power supply terminal b+ of operational amplifier A2, and out from the output terminal of operational amplifier A2. Simultaneously, it flows into the other end of inductor L (the right end), out from the left end of inductor L, and into the output terminal of operational amplifier A1. It then flows out from the negative power supply terminal a- of operational amplifier A1, returning to the negative power supply V. EE , forming a loop

[0051] At this point, the current flowing through resistor R is still from top to bottom;

[0052] First, choose a suitable value for the resistor R. When the leakage current reaches a certain specified value, the resulting current I...L As an increment, a voltage of 0.6V to 0.7V is generated across resistor R. At this time, transistor Q turns on, and the collector Ctrl of transistor Q outputs a high level.

[0053] Thus, regardless of the direction of the leakage current, this invention completes small-signal processing and finally achieves a signal output in one direction, realizing a special small-signal rectifier circuit. Full-wave rectifier circuit at the signal level The increment of the current flowing through resistor R after rectification is proportional to the detected leakage current. Internationally accepted standards set the permissible leakage current threshold at 6mA for DC power supply and 30mA for AC power supply. However, for currently popular high-power fast charging stations for new energy vehicles, the three-phase AC power is first converted into DC power (with frequency multiplication) through a PFC circuit, and then further converted to high-voltage DC power for the charging gun via a high-power converter. Currently, there is no reasonable standard for the leakage current threshold for this type of system.

[0054] In this embodiment, operational amplifiers A1 and A2 are two operational amplifiers inside an LM2904 chip, with a static operating nominal value of 1.5mA and a measured actual value of 1.46mA at a working voltage of 6V. The leakage current protection value is set at 30mA. The number of turns n of the inductor L is 30 turns, the resistor R is 240Ω, and the transistor Q is an S9015. To suppress interference, a line is drawn at the base of transistor Q. A small 100pF high-frequency ceramic capacitor is connected in parallel to the emitter stage. Here, an NPO capacitor with a 0805 package is selected. This capacitor is connected in parallel across the resistor R. Uses a single power supply, V CC 6V, V EE Grounding The two operational amplifiers are actually the two internal operational amplifiers of the LM2904, with a combined operating current of 1.46mA. Since they are powered through resistor R, if the operational amplifiers experience self-oscillation, a capacitor can be connected in parallel between the positive power supply terminal b+ and the negative power supply terminal b- of operational amplifier A2. The capacitance should be as small as possible without causing self-oscillation, so as not to affect the detection of high-frequency leakage current.

[0055] This circuit implementation uses the above parameters and is applied to a DC leakage current protector. The 1.46mA operational amplifier quiescent current flows through the 240Ω resistor R, resulting in a voltage drop of 0.263V. This voltage is applied to the base of transistor Q. At the emitter, transistor Q is not conducting and is in the cutoff state; when the leakage current is below 30mA, the current I... LThe current is less than 1mA, and when combined with the op-amp's quiescent current, it is less than 2.46mA. Flowing through the 240Ω resistor R, the resulting voltage drop is less than 0.59V. At this point, according to the PN junction equation, a weak base current flows through the transistor Q. After amplification, this forms a slightly larger current at the collector. This current must be sufficient to ensure that the trip switch or relay operates. Alternatively, the negative power supply V can be applied to the collector of transistor Q. EE A resistor is installed to absorb the current appropriately, increasing the reliability of the circuit; when the leakage current is above 30mA, the current I... L The current, greater than 1mA, combined with the op-amp's quiescent current, exceeds 2.46mA. Flowing through the 240Ω resistor R, this results in a voltage drop greater than 0.59V. At this point, according to the PN junction equation, a large base current flows through the transistor Q. After amplification, this forms an even larger current at the collector. This current is crucial to ensure the trip switch or relay operates, achieving the final goal.

[0056] When using the above parameters, this invention is applicable to DC, but is also compatible with AC applications. Actual testing shows it works normally with voltages ranging from DC to 150kHz AC. Leakage current can still be detected under 300kHz AC, but the sensitivity is reduced and the phase is shifted. The first example, tested in a DC power supply with AC power applied, still functions normally.

[0057] When there is no differential current in the parallel circuit, i.e., no leakage current, the current I in the inductor L is... L The quiescent operating current of the circuit, including the phase detector circuit of the preceding fluxgate, is zero, totaling 4.8mA. The actual power consumption is below 29mW, even when using an op-amp with a large quiescent operating current. The phase detector circuit's operating current can be easily controlled below 16mA, and the total static power consumption remains below 96mW, or below 0.1W. This is far less than the static power consumption of common high-quality single-phase AC residual current devices (RCDs): 0.23W. Currently, the static power consumption of common high-quality three-phase AC RCDs is 0.40W and above.

[0058] Another beneficial effect of this invention is its sensitive detection of high-frequency harmonic currents, which improves the safety of leakage current circuit breakers. In power supply circuits, due to the widespread use of switching power supplies and various chopper appliances, the power supply current contains many harmonic components. For example, for 50Hz AC, the 39th harmonic reaches 1950Hz. Traditional leakage current circuit breakers typically have detection coils with over 2000 turns and large distributed capacitance, resulting in significant attenuation of high-frequency harmonics. To prevent false triggering, the circuit filters out high-frequency harmonics. Traditional leakage current circuit breakers have very low sensitivity to high-frequency harmonic leakage currents. We often experience this in daily life; when using a laptop power adapter, touching the metal parts of the laptop often results in a strong electric shock. This is caused by high-frequency harmonic currents passing through the Y capacitor in the power adapter. Due to the high frequency, it flows primarily through the skin, having less impact on the heart, but over time, it still poses a significant health risk. It should be noted that many inferior power adapters or mobile phone chargers, in order to meet relevant electromagnetic compatibility standards, drastically increase the size of the Y capacitor in their internal switching power supply, greatly increasing high-frequency high-order harmonic leakage current and endangering the user's safety.

[0059] The first embodiment of this invention uses a full-wave rectifier circuit applied in a leakage current protector. This not only effectively detects DC leakage current but also effectively detects potentially hazardous high-frequency, high-order harmonic leakage currents, all at a low cost.

[0060] Because the base-emitter voltage drop of transistor Q is variable, obeying the PN junction equation, and temperature... The reverse saturation current is related to the actual base current flowing through it, which causes the circuit to react differently to different leakage currents at different temperatures. The following Example 2 addresses this issue.

[0061] Second Embodiment

[0062] Please see Figure 3 , Figure 3 This is a schematic diagram of the full-wave rectifier circuit according to the second embodiment of the present invention. The difference between the full-wave rectifier circuit in this embodiment and the first embodiment is that in this embodiment, a constant current source I is used instead of the resistor R in the first embodiment. The first end of the constant current source I is used to connect to the power supply VCC, and the second end of the constant current source I is connected to the positive power supply terminal a+ of the first operational amplifier A1 and the positive power supply terminal b+ of the second operational amplifier A2, respectively.

[0063] In this embodiment, the constant current source I can take various forms.

[0064] Please refer to Figure 4-1 , Figure 4-1 This is a schematic diagram of a constant current source implemented using a constant current diode. Pins 1 and 2 correspond to... Figure 3 Pins 1 and 2 of the constant current source I in the circuit. The abbreviation for constant current diode is CRD, which is short for Current Regulative Diode.

[0065] Please refer to Figure 4-2 , Figure 4-2 This is a schematic diagram of a constant current source implemented using a junction field-effect transistor (JFET). Pins 1 and 2 correspond to... Figure 3 Pins 1 and 2 in the diagram. A junction field-effect transistor (JFET) can also be used to implement a constant current source circuit, employing a P-channel design.

[0066] Please refer to Figure 4-3 , Figure 4-3 This is a schematic diagram illustrating the implementation of a constant current source using a junction field-effect transistor (JFET). Adjustment... Figure 4-3 The value of resistor R can be easily changed to alter the constant current value. Its pins 1 and 2 correspond to... Figure 3 Pins 1 and 2 in the diagram. A junction field-effect transistor (JFET) can also be used to implement a constant current source circuit, employing a P-channel design.

[0067] Please refer to Figure 4-4 , Figure 4-4 The schematic diagram shows a classic circuit using two PNP transistors connected as a constant current source. Its output current is approximately:

[0068] ……………………………………………………………………Formula (3)

[0069] In the formula, Io is Figure 4-4 The output current of pin 2, U BE This is the base-emitter voltage drop of transistor TR202; for silicon transistors, it is typically around 0.6V. 201 Let R201 be the resistance value. This circuit can also be implemented using an NPN transistor.

[0070] When the amplification factor of transistors TR201 and TR202 is large, the value of R202 in the circuit can be larger, thus optimizing the circuit into a two-terminal device for ease of use. For example... Figure 4-5 As shown, its constant current performance is slightly worse than... Figure 4-4 The circuit is suitable for applications with less demanding requirements.

[0071] Please refer to Figure 4-6 , Figure 4-6This is a schematic diagram of a constant current source constructed using the TL431 precision adjustable reference integrated circuit. A constant current source can be implemented using other precision adjustable reference integrated circuits, such as the TL432, whose output current is approximately:

[0072] ……………………………………………………………… Formula (4)

[0073] In the formula, Io is Figure 4-6 The output current of pin 2, V REF The reference voltage for a precision adjustable reference integrated circuit is typically 2.50V, 2.495V, or 1.25V. R 301 This is the resistance value of resistor R301.

[0074] Please refer to Figure 4-7 , Figure 4-7 The schematic diagram shows a constant current source constructed using the LM317 voltage regulator integrated circuit. A constant current source can also be implemented using other linear voltage regulator circuits. Its output current is approximately:

[0075] ……………………………………………………Formula (5)

[0076] In the formula, Io is Figure 4-7 The output current at pin 2 is 1.20V, which is the reference voltage of the LM317. Early LM317s had a reference voltage of around 1.25V, which was later reduced to around 1.20V. R 301 This is the resistance value of resistor R301.

[0077] It should be noted that when the detection device is a common bipolar transistor, the operating voltage drop of the constant current source I must be below 0.6V. Figure 4-1 Figure 4-2 Figure 4-3 and Figure 4-4 A constant current source can be used; Figure 4-5 Figure 4-6 Figure 4-7 The constant current source has a large voltage drop during operation, so a more special method is required for its use in the second embodiment. High-cost components, such as Figure 4-5 In such circuits, transistors with extremely high amplification factors, above 300, are required. This ensures that the value of resistor R302 is large enough to maintain constant current performance. However, such high-amplification transistors experience a decrease in thermal stability. Figure 4-6In the circuit diagram, the TL431 should be selected with a low reference voltage; otherwise, the voltage drop of the entire constant current source will be too large, reducing the overall efficiency. Even if a common 1.25V low reference voltage model of the TL431 is selected, Figure 4-6 The voltage drop of the constant current source circuit is also above 2V. If the TL431 with a reference voltage of 0.866V is selected, it is a special component, which requires customization, significantly increasing the cost; while Figure 4-7 In this constant current source circuit, the LM317's minimum operating voltage drop is 2.0V (actual value; the datasheet specifies 2.5V). Adding the 1.20V across resistor R301, the total is 3.20V. Excessive operating voltage drop reduces the overall efficiency of the constant current source. Lowering the voltage drop and reference voltage of the LM317 would require custom-made components, significantly increasing costs. When the sensing device is a field-effect transistor... Due to its turn-on voltage V GS Relatively high Figures 4-1 to 4-7 All the constant current sources mentioned can be used.

[0078] For convenience, the constant current value of constant current source I is selected by assuming I1 is the total current, and the total current is equal to I. L Add the quiescent operating current I of operational amplifiers A1 and A2 A1 and I A2 , while I L Equal to the leakage current I to be set S Divide by the number of turns n of the inductor L, then:

[0079] ……………………Formula (5)

[0080] In this embodiment, the set operating leakage current IS is 23mA, the inductor L has 100 turns, and the operational amplifiers A1 and A2 are TL062. TL062 is a low-power dual operational amplifier with a nominal sum of its static operating currents IA1 and IA2 of 0.2mA, which is measured to be 0.19mA at a 6V operating voltage. The transistor Q is an FMMT591. Therefore, the constant current value of the constant current source I is equal to I1, which should be: I1 = (23 / 100) + 0.19 = 0.42 (mA). Considering that the leakage current accuracy requirement of the leakage current protector is not high in actual use, generally ±15% is sufficient, this facilitates the selection of the constant current source. Here, the S-701T constant current transistor produced by SEMITEC is selected. There are many domestic alternatives of the same model. The nominal constant current rating (IP) of this model of constant current tube is 0.7mA, and the test voltage for the nominal IP rating is 10V, which is relatively high. The manufacturer's technical manual specifies another parameter: the turn-on voltage VK, which refers to the terminal voltage when the operating current rises to 0.8 times the nominal value IP. In fact, below the turn-on voltage, the constant current transistor can still operate at a relatively small current. Measured current flowing through the S-701T was 0.39mA, with a voltage drop of 0.6V; and when the current was 0.42mA, the voltage drop was 0.68V. A characteristic of the constant current source is that when the actual operating current is less than its nominal value, the internal transistor used for constant current conduction is essentially saturated, making it suitable for this embodiment.

[0081] The working principle of the full-wave rectifier circuit in this embodiment is as follows:

[0082] The second implementation circuit uses the above parameters and is applied to a DC leakage current protector. A 0.19mA operational amplifier quiescent current flows through the constant current source I, resulting in a measured voltage drop of 0.39V. This voltage is applied to the base of transistor Q. At the emitter, transistor Q is not conducting and is in the cutoff state; at this moment, the corresponding leakage current is zero.

[0083] When the leakage current is below 23mA, the current IL is less than 0.23mA. Combined with the operational amplifier's quiescent current, it is less than 0.42mA. Flowing through the constant current source I, the resulting voltage drop is less than 0.68V. At this point, a weak base current flows through the base of transistor Q according to the PN junction equation. After amplification, this forms a slightly larger current at the collector. This current must be sufficient to trigger the trip switch or relay. Alternatively, a resistor can be placed between the collector and VEE terminals of transistor Q to absorb this current and increase the circuit's reliability.

[0084] When the leakage current exceeds 23mA, the current IL is greater than 0.23mA. Combined with the operational amplifier's quiescent current, this exceeds 0.42mA. Flowing through the constant current source I, the resulting voltage drop is greater than 0.68V. At this point, according to the PN junction equation, a large base current flows through the base of transistor Q. After amplification, this forms an even larger current at the collector. This current must ensure the trip switch or relay operates, achieving the final goal.

[0085] The second embodiment of the present invention uses a full-wave rectifier circuit applied in a leakage current protector. This not only enables effective detection of DC leakage current, but also effectively detects potentially hazardous high-frequency, high-order harmonic leakage currents, and is cost-effective.

[0086] Because the base-emitter voltage drop of transistor Q is variable, obeying the PN junction equation, and temperature... The reverse saturation current and the actual base current flowing through the transistor are related, which causes the circuit to react differently to different leakage currents at different temperatures. For example, in this embodiment, when the leakage current is 23mA, the voltage drop across the constant current source I is 0.68V. If the ambient temperature is low, the emitter of transistor Q will... A large base voltage drop causes the transistor to enter the cutoff region or even turn off completely; when the ambient temperature reaches 75 degrees Celsius, the emitter of transistor Q... The base forward voltage drop is actually low, causing the transistor to enter the amplification region or even saturate. This results in the tripping of switches or relays in the circuit, creating a significant ambiguity, which is unacceptable for a good product. Example 3 below addresses this issue by using an operational amplifier or comparator to eliminate the ambiguity.

[0087] Third Embodiment

[0088] Please see Figure 5 , Figure 5 This is a schematic diagram of the full-wave rectifier circuit according to the third embodiment of the present invention. The difference between the full-wave rectifier circuit in this embodiment and the first embodiment is that, in this embodiment, the detection device is the third operational amplifier A3. The inverting input terminal and the negative power supply terminal c- of the third operational amplifier A3 are used as ports of the detection device. The inverting input terminal of the third operational amplifier A3 is connected to the second end of the resistor R. The first end of the resistor R is connected to the negative power supply terminal c- of the third operational amplifier A3, and is also connected to the negative power supply VEE or ground. The second end of the resistor R is connected to the negative power supply terminal a- of the first operational amplifier A2 and the negative power supply terminal b- of the second operational amplifier A2. That is, the detection of the first and second operational amplifiers A1 and A2 is performed by connecting the first and second operational amplifiers A1 and A2. The resistor R for A2's operating current can be moved to the negative power supply VEE or grounded. The detailed connection relationship is as follows:

[0089] The full-wave rectifier circuit in this embodiment includes: a first operational amplifier A1 Second op-amp A2 Inductor L The resistor R and the sensing device, wherein the sensing device is the third operational amplifier A3; the first, second, and third operational amplifiers A1, A2, and A3 are hereinafter referred to as operational amplifier A1, operational amplifier A2, and operational amplifier A3 in this embodiment. The input terminal of operational amplifier A1 is connected to the input voltage signal. The output terminal of operational amplifier A1 is connected to one end of inductor L. The positive power supply terminal a+ of operational amplifier A1 is connected to the positive power supply terminal b+ of operational amplifier A2, and the negative power supply terminal a- of operational amplifier A1 is connected to the negative power supply terminal b- of operational amplifier A2. The input terminal of operational amplifier A2 is connected to the reference voltage source, and the output terminal of operational amplifier A2 is connected to the other end of inductor L. The power supply V... CCThe resistor R is connected to the positive power supply terminal a+ of op-amp A1 and the positive power supply terminal b+ of op-amp A2. The first end of the resistor R is connected to the negative power supply V. EE Alternatively, operational amplifiers A1 and A2 are connected to the negative power supply V through resistor R. EE Alternatively, ground; the two detection ports of the detection device are connected in parallel across the two ends of resistor R. Specifically, the inverting input terminal of operational amplifier A3 is connected to the second end of resistor R, the negative power supply terminal b- of the second operational amplifier A2 is connected to the second end of resistor R, the negative power supply terminal C- of operational amplifier A3 is connected to the first end of resistor R, and the non-inverting input terminal of operational amplifier A3 is connected to the reference voltage V. ref The power supply terminal of op-amp A3 is connected to the power supply V. CC The output terminal Ctrl of other power amplifier A3 is used to output the full-wave rectified signal after full-wave rectification of the input voltage signal.

[0090] The op-amp A3 mentioned above can also be replaced with a comparator. The difference between a comparator and an op-amp will be explained in detail here.

[0091] 1 Op-amps can be connected to form a comparator output; a comparator is essentially a comparison unit.

[0092] 2 The output stage of an operational amplifier typically uses a complementary push-pull circuit. The comparator output is usually an open-collector output, i.e., an OC output, which facilitates level conversion and requires a pull-up resistor. The unipolar output is easy to connect to digital circuits and can easily output TTL levels.

[0093] 3 The comparator lacks phase compensation circuitry, resulting in a higher slew rate than comparable op-amps. However, because it lacks internal phase compensation, it is prone to self-oscillation when connected as an amplifier. The open-loop gain of a comparator is much higher than that of a typical amplifier, so even a small difference between the positive and negative terminals of the comparator will cause a change in the output.

[0094] 4 Comparators have fast switching speeds, on the order of nanoseconds, while op-amps typically have switching speeds on the order of microseconds, except for special high-speed op-amps. This characteristic does not affect the present invention.

[0095] Based on the above distinction between comparators and operational amplifiers, in this invention, operational amplifier A3, the comparator and operational amplifier are interchangeable; that is, in this invention, operational amplifier A3 also includes a comparator. The common LM393, similar to a non-adjustable operational amplifier, is used as op-amp A3 in this invention to achieve the same purpose.

[0096] Op-amps A1 and A2 are two op-amps internal to an LM358 chip. Their static operating nominal value is 700uA, but the actual measured value at 5V is 0.65mA. CC 5V, V EE Grounding The two operational amplifiers are powered by resistor R. If the operational amplifiers self-oscillate, a capacitor can be connected in parallel between the positive power supply terminal b+ and the negative power supply terminal b- of operational amplifier A2. The capacitance should be as small as possible without affecting the detection of high-frequency leakage current, provided that self-oscillation is not prevented. The leakage current protection value is set at 6mA. The number of turns n of the inductor L is 12 turns, and the resistor R is 100Ω. Q in the diagram represents operational amplifier A3. An LM393 comparator is selected, using the aforementioned single power supply V. CC Power supply: The reference voltage V connected to the non-inverting input of the LM393. ref The voltage is 0.115V. Here, a 510K resistor and a 12K resistor are connected in series and then in parallel to a 5V power supply. The 12K resistor is grounded, and the 510K resistor is connected to the 5V power supply. CC The connection point is connected to the non-inverting input of the LM393, and its connection point is a reference voltage of 0.115V to ground.

[0097] The 0.115V reference voltage is derived from the above formula (2). In this embodiment, the operating leakage current I to be set is... S The current is 6mA, the inductor L has 12 turns, and the quiescent operating current I of operational amplifiers A1 and A2 is... A1 and I A2 The sum of the nominal values ​​is 0.65mA. Therefore, the maximum value of the current I1 flowing through resistor R should be: I1 = (6 / 12) + 0.65 = 1.15 (mA). The maximum voltage drop across the 100Ω resistor R is U1 = I1R = 1.15mA × 100Ω = 0.115V.

[0098] It's important to note that when selecting the A3 op-amp, whether it's an operational amplifier or a comparator, for single-supply operation, a model with an input voltage starting from 0V should be chosen. Generally, if its internal differential stage consists of a PNP transistor or a P-type MOSFET, it's acceptable, such as the LM2904 or LM358. For a detailed introduction to operational amplifiers, please refer to Chinese application No. 201110218012.8. Figure 5 Figure 6 And the instruction manual contains a detailed description in paragraphs

[0036] to

[0039] .

[0099] The working principle of the full-wave rectifier circuit in this embodiment is as follows:

[0100] If the current IL in the inductor L flows from left to right, then op-amp A1 outputs current, while the output pin of op-amp A2 receives the current flowing in. Absorbing current The power supply current VCC flows into the positive power supply terminal a+ of operational amplifier A1, exits from the output terminal of operational amplifier A1, and simultaneously flows into one end of inductor L (the left end), exits from the right end of inductor L, is injected into the output terminal of operational amplifier A2, exits from the negative power supply terminal b- of operational amplifier A2, and returns to the negative power supply VEE through resistor R, forming a circuit. The power supply VCC and the negative power supply VEE are equivalent to the positive and negative terminals of a battery.

[0101] At this time, the current I1 flowing through resistor R is from top to bottom;

[0102] If the current IL in the inductor L flows from right to left, then op-amp A2 outputs current, while the output pin of op-amp A1 receives the current flowing in. Absorbing current The power supply current VCC flows into the positive power supply terminal b+ of operational amplifier A2, exits from the output terminal of operational amplifier A2, and simultaneously flows into the other end of inductor L (the right end), exits from the left end of inductor L, is injected into the output terminal of operational amplifier A1, exits from the negative power supply terminal a- of operational amplifier A1, and returns to the power supply VEE terminal through resistor R, forming a circuit.

[0103] At this point, the current I1 flowing through resistor R is still from top to bottom;

[0104] Thus, regardless of the direction of the leakage current, this invention completes small-signal processing and finally achieves a signal output in one direction, realizing a special small-signal rectifier circuit.

[0105] First, select a suitable value for the resistor R. When the leakage current reaches the specified threshold, the resulting current I... L The total current is I1, which is the increment. The voltage generated across resistor R is connected to the inverting input of operational amplifier A3. When the leakage current is within limits, this voltage is below 0.115V, the non-inverting input of operational amplifier A3 is 0.115V, and the output of operational amplifier A3 is high, so the trip switch or relay does not operate. When the leakage current exceeds limits, the voltage generated across resistor R is above 0.115V. The non-inverting input of operational amplifier A3 remains at 0.115V, while the inverting input is relatively high, and the output of operational amplifier A3 is low, driving the trip switch or relay to operate, causing the leakage current protector to cut off the power supply.

[0106] In this embodiment, replacing resistor R with a constant current source with an actual operating current of 1.15mA also allows for normal operation. The constant current source can be the one corresponding to the one in the second embodiment. Figure 4-6 In order to make the constant current source have two terminals, the disclosed part of the circuit sacrifices the constant current performance. Here it has been restored to its original appearance, see [link / reference] Figure 5-1 To obtain a precise constant current source of 1.15mA and a low voltage drop, the precision adjustable reference integrated circuit selected is the TLV431A with a reference voltage of 1.24V. Figure 4-6 The upper terminal of resistor R302, which was originally connected to the collector of transistor TR301, is now connected to the power supply V. CC The TR301 uses the S9014, which has an amplification factor of over 300 and a saturation voltage drop of 0.15V. Figure 5-1 In the circuit 1 The constant current source with two terminals has a turn-on voltage of (1.24V + 0.15V) = 1.39V or higher. The minimum operating voltage of op-amps A1 and A2 (LM358) is 5V, but they can actually operate up to 3.6V. Op-amp A3, however, has a minimum operating voltage of 3V and is unaffected. Therefore, in order to ensure the normal operation of the LM358, the power supply V CC For a voltage rating of 6.4V or higher, we'll use 8V here. Therefore, R302 can be selected from 6.2k to 56kΩ, and all tests show it works normally. R301 is a 1.078kΩ resistor, but this value is not standard; it's actually obtained by connecting a 1.1kΩ resistor in parallel with a 56kΩ resistor. Meanwhile, the reference voltage V connected to the non-inverting input of operational amplifier A3 (LM393 comparator) ref The voltage is adjusted to 1.5V. Here, a 130K resistor and a 30K resistor are connected in series and then in parallel to the 8V power supply. The 30K resistor is grounded, and the 130K resistor is connected to the 8V power supply. CC The connection point is connected to the non-inverting input of the LM393, and its connection point is a 1.5V reference voltage to ground. Actual measurement Figure 4-1 Circuit 1 The constant current source with terminals 2 is 1.15mA and has a turn-on voltage of 1.33V. It is used to replace resistor R in Figure 4. In this embodiment, attention should be paid to the current direction during replacement. Terminal 1 of the constant current source replaces terminal 2 of resistor R, and terminal 2 of the constant current source replaces terminal 1 of resistor R. It is not dogmatic to simply replace terminal 1 of resistor R with terminal 2. Use 2 to remove the second end of resistor R.

[0107] After power-on, the circuit performs all its functions with extremely low temperature drift and stable performance.

[0108] Fourth embodiment

[0109] Please see Figure 6 , Figure 6 This is a schematic diagram of the full-wave rectifier circuit according to the fourth embodiment of the present invention. The difference between the full-wave rectifier circuit in this embodiment and the first embodiment is that, in this embodiment, the detection operational amplifier A1 is... The resistor R for the A2 operating current is switched to the ground terminal VEE, and the sensing device is changed from a PNP transistor to an NPN transistor; the difference from the third embodiment is that in this embodiment, the sensing device is changed from the third operational amplifier A3 to an NPN transistor.

[0110] The detailed connection relationships are as follows. The full-wave rectifier circuit in this embodiment includes:

[0111] First op-amp A1 Second op-amp A2 Inductor L Resistor R and sensing device Q The input terminal of the first operational amplifier A1 is connected to the input voltage signal, and the output terminal of the first operational amplifier A1 is connected to one end of the inductor L. The positive power supply terminal a+ of the first operational amplifier is connected to the positive power supply terminal b+ of the second operational amplifier A2, and the negative power supply terminal a- of the first operational amplifier A1 is connected to the negative power supply terminal b- of the second operational amplifier A2. The input terminal of the second operational amplifier A2 is connected to the reference voltage source, and the output terminal of the second operational amplifier A2 is connected to the other end of the inductor L. The power supply V... CC The first terminal of resistor R is connected to the positive power supply terminal a+ of the first operational amplifier A1 and the positive power supply terminal b+ of the second operational amplifier A2. The first terminal of resistor R is connected to the negative power supply V. EE Alternatively, the negative power supply terminal b- of the second operational amplifier A2 is connected to the second end of the resistor R, meaning that the first operational amplifier A1 and the second operational amplifier A2 are connected to the negative power supply V through the resistor R. EE Alternatively, grounding may be used. In this embodiment, the detection device is a transistor Q, specifically an NPN transistor. The emitter and base of transistor Q serve as detection ports. The emitter of transistor Q is connected to the first terminal of resistor R, and the base of transistor Q is connected to the second terminal of resistor R. The collector of transistor Q is used to output the full-wave rectified signal obtained by full-wave rectification of the input voltage signal.

[0112] The fourth embodiment is essentially an equivalent substitution of the first embodiment, replacing the detection operational amplifier A1. The resistor R for A2's operating current is moved to the ground terminal VEE, and is connected in series with the op-amp. Resistor R can be considered as the power supply resistor, only now it's changed from being connected in series with the positive power supply to being connected in series with the negative power supply. Therefore, the transistor Q, acting as the sensing device, should change its polarity from PNP to NPN.

[0113] Therefore, the working principle of this embodiment will not be analyzed in detail.

[0114] Fifth Embodiment

[0115] Please see Figure 7 , Figure 7 This is a schematic diagram of the full-wave rectifier circuit according to the fifth embodiment of the present invention. The difference between the full-wave rectifier circuit in this embodiment and the third embodiment is that, in this embodiment, the detection of the first and second operational amplifiers A1 is... The resistor R for A2's operating current is switched to the power supply VCC, and the reference voltage connected to the non-inverting input of the third operational amplifier A3 is changed to be based on the power supply VCC.

[0116] The fifth embodiment is essentially an equivalent substitution of the third embodiment, replacing the detection operational amplifier A1. The resistor R for A2's operating current is switched to the power supply VCC, and the op-amp A1 is connected to it. A2 is connected in series, and the resistor R is considered as the power supply resistor, except that it is no longer connected in series with the negative power supply, but in series with the positive power supply. Therefore, the reference voltage Vref connected to the non-inverting input of the third operational amplifier A3, which acts as the detection device, is now based on the power supply VCC.

[0117] Therefore, the working principle of this embodiment will not be analyzed in detail.

Claims

1. A full-wave rectifier circuit, characterized in that, Includes: First op-amp The system comprises a second operational amplifier, an inductor, a resistor, and a detection device. The input terminal of the first operational amplifier is connected to an input voltage signal, and the input terminal of the second operational amplifier is connected to a reference voltage source. The power supply terminals of the first and second operational amplifiers are connected in parallel. The output terminal of the first operational amplifier is connected to one end of the inductor, and the other end of the inductor is connected to the output terminal of the second operational amplifier. The resistors are connected to the power supply terminals of the first operational amplifier and the second operational amplifier, respectively, and the power supply provides power to the first operational amplifier and the second operational amplifier through the resistors; the detection port of the detection device is connected in parallel with the resistors, and the detection device is used to output a full-wave rectified signal.

2. The full-wave rectifier circuit according to claim 1, characterized in that, The first end of the resistor is used to connect to the power supply, and the second end of the resistor is connected to the power supply terminal of the first operational amplifier and the power supply terminal of the second operational amplifier, respectively.

3. The full-wave rectifier circuit according to claim 1, characterized in that, The detection device is a transistor, with the emitter and base of the transistor serving as the detection ports. The emitter of the transistor is connected to the first end of the resistor, and the base of the transistor is connected to the second end of the resistor.

4. The full-wave rectifier circuit according to claim 1, characterized in that, The detection device is an operational amplifier. The inverting input terminal and the power supply terminal of the operational amplifier serve as the detection port. The inverting input terminal of the operational amplifier is connected to the second end of the resistor, and the power supply terminal of the operational amplifier is connected to the first end of the resistor.

5. A full-wave rectifier circuit, characterized in that, Includes: First op-amp The system comprises a second operational amplifier, an inductor, a constant current source, and a detection device. The input terminal of the first operational amplifier is connected to an input voltage signal, and the input terminal of the second operational amplifier is connected to a reference voltage source. The same-polarity power supply terminals of the first and second operational amplifiers are connected in parallel. The output terminal of the first operational amplifier is connected to one end of the inductor, and the other end of the inductor is connected to the output terminal of the second operational amplifier. The constant current source is connected to the power supply terminals of both the first and second operational amplifiers, and the power supply provides power to both operational amplifiers through the constant current source. The detection port of the detection device is connected in parallel with the constant current source, and the detection device outputs a full-wave rectified signal.

6. The full-wave rectifier circuit according to claim 5, characterized in that, The first end of the constant current source is used to connect to the power supply, and the second end of the constant current source is connected to the power supply terminal of the first operational amplifier and the power supply terminal of the second operational amplifier, respectively.

7. The full-wave rectifier circuit according to claim 5, characterized in that, The detection device is a transistor, with the emitter and base of the transistor serving as the detection ports. The emitter of the transistor is connected to the first end of the constant current source, and the base of the transistor is connected to the second end of the constant current source.

8. The full-wave rectifier circuit according to claim 5, characterized in that, The detection device is an operational amplifier or a comparator. The inverting input terminal and the power supply terminal of the operational amplifier or the comparator serve as the detection port. The inverting input terminal of the operational amplifier or the comparator is connected to the second terminal of the constant current source, and the power supply terminal of the operational amplifier or the comparator is connected to the first terminal of the constant current source.

9. The full-wave rectifier circuit according to claim 5, characterized in that, The current of the constant current source is above the total current, which is the sum of the static operating current of the first operational amplifier, the static operating current of the second operational amplifier, and the leakage current threshold divided by the number of turns of the inductor coil.

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