An independent superimposed constant current source power combiner

Abstract

The application discloses an independent superposition type constant current source power combiner, which comprises a power combination circuit and a safety protection circuit; the power combination circuit comprises N constant current source modules and a first operational amplifier; the N constant current source modules are connected with the first operational amplifier after being connected in parallel with each other; N is a positive integer greater than 1; the safety protection circuit comprises a wire or circuit, a compound transistor and a voltage limiting protection circuit; the wire or circuit is connected with the voltage limiting protection circuit, and the voltage limiting protection circuit is connected with the compound transistor; the N constant current source modules are connected with the wire or circuit; the application solves the problems of uneven transistor current distribution, complex structure and low reliability in the prior art.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of constant current source power synthesis, and more particularly to an independent superposition type constant current source power synthesizer. BACKGROUND

[0002] At present, high-power constant current sources are widely used in semiconductor laser driver, various charging devices and scientific experiments, and the existing implementation methods mainly use a single high-power transistor or field effect transistor as the core device.

[0003] However, in the actual use process, there are problems of high power consumption of single tube, large heat dissipation system and low reliability. One solution is to use multiple transistors or field effect transistors in parallel to share the working current, and at the same time, a certain redundancy is added. This solution has the problem of uneven distribution of current among the transistors, some transistors have large working current and some transistors have small working current, which cannot completely solve the problem of low reliability of single tube; another solution is to select and group transistors according to parameters, but the consistency of high-power transistors is poor, the selection is difficult, resulting in low work efficiency, and the use of multiple transistors in parallel has poor balance, some transistors have large current and some transistors have small current, the transistors with large working current are easily damaged, and the damage of one transistor will cause the whole to stop working, which requires safety protection measures, making the constant current source circuit structure complex and increasing the system failure rate.

[0004] Therefore, how to avoid uneven distribution of transistor current in the existing high-power constant current source and complex structure and low reliability is a problem that those skilled in the art need to solve. SUMMARY

[0005] Therefore, the present application provides an independent superposition type constant current source power synthesizer, which solves the problem of uneven distribution of transistor current in the existing high-power constant current source and complex structure and low reliability.

[0006] In order to achieve the above purpose, the present application adopts the following technical scheme:

[0007] An independent superposition type constant current source power synthesizer, comprising: a power synthesis circuit and a safety protection circuit;

[0008] The power synthesis circuit comprises: N constant current source modules and a first operational amplifier; N constant current source modules are connected with the first operational amplifier in parallel; N is a positive integer greater than 1;

[0009] The safety protection circuit comprises: a wire or circuit, a composite transistor and a voltage limiting protection circuit; the wire or circuit is connected with the voltage limiting protection circuit, and the voltage limiting protection circuit is connected with the composite transistor;

[0010] N constant current source modules are connected with the line or circuit.

[0011] Preferably, the constant current source module comprises a second operational amplifier, a first transistor, a first resistor and a second resistor.

[0012] The output end of the second operational amplifier is connected with the base of the first transistor.

[0013] The inverting input end of the second operational amplifier is connected with the emitter of the first transistor and then grounded through the second resistor.

[0014] The collectors of the N first transistors are connected in parallel and then connected with the constant current source through a load resistor.

[0015] The non-inverting input ends of the N second operational amplifiers are connected with the first resistor and then connected in parallel with each other.

[0016] Preferably, the N constant current source modules are of the same circuit structure, and the first operational amplifier, the first transistor, the first resistor and the second resistor in each constant current source module are all the same.

[0017] Preferably, the line or circuit comprises N diodes and a third resistor.

[0018] The N diodes are connected in parallel and then connected with the voltage limiting protection circuit, and the connection node of the diodes and the voltage limiting protection circuit is grounded through the third resistor.

[0019] The anodes of the N diodes are respectively connected with the second resistors in the N constant current source modules.

[0020] Preferably, the voltage limiting protection circuit comprises a first stabilizing diode and a fourth resistor.

[0021] The cathode of the first stabilizing diode and one end of the fourth resistor are connected.

[0022] The anode of the first stabilizing diode is grounded.

[0023] The cathodes of the N diodes are connected in parallel with each other and then connected with the other end of the fourth resistor.

[0024] Preferably, the composite transistor comprises a second transistor and a third transistor.

[0025] The emitter of the second transistor is connected with the base of the third transistor.

[0026] The base of the second transistor is connected with one end of the fourth resistor, and the connection node of the base of the second transistor and the fourth resistor is connected with the cathode of the first stabilizing diode.

[0027] The third transistor emitter is grounded.

[0028] Preferably, the first operational amplifier output end is connected with a first resistor in the N constant current source modules; the first operational amplifier inverting input end is connected with the first operational amplifier output end; and the first operational amplifier non-inverting input end is connected with an adjusting power supply.

[0029] Preferably, the power synthesis circuit further comprises a second voltage stabilizing diode and a first capacitor.

[0030] The first operational amplifier output end is connected with a connection node of the N first resistors, and the connection node is connected with a cathode of the second voltage stabilizing diode.

[0031] The anode of the second voltage stabilizing diode is grounded.

[0032] The first operational amplifier output end is connected with a connection node of the N first resistors, and the connection node is connected with a cathode of the second voltage stabilizing diode.

[0033] Preferably, the safety protection circuit further comprises a second capacitor.

[0034] The second transistor base is connected with one end of the fourth resistor, and a connection node of the second transistor base and the fourth resistor is connected with the second capacitor and then grounded.

[0035] Preferably, the safety protection circuit further comprises a relay.

[0036] The first end of the relay is connected with the second transistor collector and the third transistor collector respectively.

[0037] The second end of the relay is connected with the constant current source.

[0038] The third end of the relay is connected with the power supply.

[0039] As can be seen from the above technical solution, compared with the prior art, the present invention discloses an independent superimposed constant current source power combiner. It employs independent constant current source modules for balanced superposition and synthesis, ensuring uniform current distribution across all modules and enabling balanced synthesis of large currents. A line or circuit is used as a safety protection circuit, and a composite transistor provides a large drive current, guaranteeing reliable relay operation. All circuits are implemented entirely in hardware, resulting in fast response, simple circuit structure, and high reliability, making it widely applicable to systems driven by high-power constant current sources. The number of constant current source modules is determined based on the total current, providing strong scalability, and redundancy is appropriately added to ensure the overall safety and reliability of the constant current source. This technical solution solves key technical problems in the design of high-power constant current sources, achieving balanced linear superposition to meet the demand for large output currents. It also modularizes, standardizes, and serializes the design process, providing strong scalability and applicability to various high-power constant current source applications. Attached Figure Description

[0040] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0041] Figure 1 The attached figure is a schematic diagram of the independent superimposed constant current source power synthesizer provided by the present invention.

[0042] Figure 2 The attached figure is a schematic diagram of the power combining circuit provided by the present invention.

[0043] Figure 3 The attached figure is a schematic diagram of the safety protection circuit provided by the present invention. Detailed Implementation

[0044] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0045] like Figure 1 As shown, this embodiment of the invention discloses an independent superimposed constant current source power combiner, including: a power combining circuit and a safety protection circuit;

[0046] The power synthesis circuit comprises N constant current source modules and a first operational amplifier; the N constant current source modules are connected with the first operational amplifier after being connected in parallel with each other; N is a positive integer greater than or equal to 1.

[0047] The safety protection circuit comprises a wire or circuit, a compound transistor and a voltage limiting protection circuit; the wire or circuit is connected with the voltage limiting protection circuit, and the voltage limiting protection circuit is connected with the compound transistor.

[0048] The N constant current source modules are connected with the wire or circuit.

[0049] Another embodiment of the present application discloses an independent superimposed constant current source power synthesizer, which comprises a power synthesis circuit and a safety protection circuit.

[0050] As shown in Figure 2 The power synthesis circuit comprises N constant current source modules and a first operational amplifier AK; the N constant current source modules are connected with the first operational amplifier after being connected in parallel with each other; N is a positive integer greater than 1.

[0051] Preferably, the constant current source module comprises a second operational amplifier AN, a first transistor TN, a first resistor RCN and a second resistor RDN.

[0052] The output end of the second operational amplifier AN is connected with the base of the first transistor TN.

[0053] The inverting input end of the second operational amplifier AN is connected with the emitter of the first transistor TN and then grounded through the second resistor RDN.

[0054] The collectors of the first transistors TN in the N constant current source modules are connected in parallel with each other and then connected with a constant current source VC through a load resistor RL.

[0055] The non-inverting input ends of the second operational amplifiers AN in the N constant current source modules are connected with the first resistors RCN and then connected in parallel with each other.

[0056] Preferably, the second operational amplifier AN is a general integrated operational amplifier, which is an electronic integrated circuit containing multiple-stage amplification circuits, the input stage of which is a differential amplification circuit, has a high input resistance and a zero-point drift suppression capability; the middle stage mainly performs voltage amplification, has a high voltage amplification multiple, and is generally composed of a common-emitter amplification circuit; the output stage is connected with a load, has a strong load capacity and a low output resistance.

[0057] Preferably, the N constant current source modules connected in parallel with each other all have the same circuit structure, and the second operational amplifiers AN, the first transistors TN, the first resistors RCN and the second resistors RDN in each constant current source module are all the same.

[0058] Preferably, the first resistor RCN is an input isolation resistor of the second operational amplifier AN, and functions as an isolation and buffer.

[0059] Preferably, the first resistor RCN has a resistance value of the order of kilo-ohms.

[0060] Preferably, the first resistor RCN has a resistance value greater than that of the second resistor RDN.

[0061] Preferably, the second resistor RDN is a sampling resistor, and a sampling voltage on the sampling resistor RDN is VN.

[0062] Preferably, the second resistor RDN is a precision sampling resistor, and a resistance value of the precision sampling resistor RDN is less than 1 ohm, so that the resistance value is not too large to cause excessive power consumption and a voltage drop across the precision sampling resistor RDN is not too large.

[0063] Preferably, the precision resistor has a low temperature drift characteristic: the lower the temperature coefficient TCR value, the higher the stability; and a high precision characteristic: the higher the precision, the lower the TCR value, and the higher the stability, and the precision is 0.01% to 1%.

[0064] Preferably, the second resistor RDN determines the output current IN of the independent constant current source module.

[0065] Preferably, the first transistor TN implements a current expansion function of the second operational amplifier AN, and is equivalent to a final stage circuit unit of the operational amplifier AN.

[0066] Preferably, the second operational amplifier AN and the first transistor TN are connected to form an emitter follower structure.

[0067] Preferably, an output end of the first operational amplifier AK is connected to the first resistors RD1 to RDN in the N constant current source modules respectively; an inverting input end of the first operational amplifier AK is connected to the output end of the first operational amplifier AK; and a non-inverting input end of the first operational amplifier AK is connected to an adjusting power supply.

[0068] Preferably, the first operational amplifier AK is a general-purpose operational amplifier, and is the same as the second operational amplifier AN in each constant current source module.

[0069] Preferably, the first operational amplifier AK is a general-purpose operational amplifier, and is selected to be of another model different from the second operational amplifier AN in each constant current source module.

[0070] Preferably, a voltage of the adjusting power supply is a total control and adjusting voltage Vi of the synthesized constant current source, and a total output current is determined by the total control and adjusting voltage Vi.

[0071] Preferably, the total control and adjusting voltage Vi simultaneously acts on input control ends in each constant current source module, so that each constant current source module can be conveniently expanded according to the size of the total output current.

[0072] Preferably, the first operational amplifier AK is connected in full feedback form to constitute a voltage follower, which has an amplification factor of 1, functions as a buffer isolator, has high input impedance, low output impedance, and sufficient driving capacity to provide sufficient driving current for each constant current source module.

[0073] Preferably, according to the basic principle of an emitter follower, the following relationship can be obtained:

[0074] The output voltage VK of the first operational amplifier AK is the same as the total control and regulation voltage Vi.

[0075] The output voltage VK of the first operational amplifier AK is the same as the sampling voltage VN on the second resistor RDN.

[0076] The output current IN of the independent constant current source module is VN / RDN=V1 / RD1.

[0077] Preferably, since VK=Vi, VK=VN=V1, the total output current IM of the superimposed constant current source power combiner is:

[0078]

[0079] Preferably, the number of constant current source modules is designed according to the current IN of each constant current source module and the total current IM, and redundancy is left in actual application to ensure the safety and reliability of the overall constant current source.

[0080] Preferably, the power combining circuit further comprises a second zener diode DA and a first capacitor C1.

[0081] The connection node of the output end of the first operational amplifier AK and the N first resistors RCN is connected to the cathode of the second zener diode DA.

[0082] The anode of the second zener diode DA is connected to ground.

[0083] The connection node of the output end of the first operational amplifier AK and the N first resistors RCN is connected to the first capacitor C1 and then to ground.

[0084] Preferably, the second zener diode DA is a varistor diode, which is used to absorb transient voltage spikes and protect the subsequent constant current source modules.

[0085] Preferably, the varistor diode DA is a special zener diode, which maintains a constant voltage when the voltage exceeds the peak clipping voltage; it is mainly used to absorb the peak interference of the input signal of the previous stage and protect the subsequent circuit; the peak clipping voltage is not more than the maximum common mode voltage of the subsequent operational amplifier.

[0086] Preferably, the first capacitor C1 is a high-frequency capacitor, which is used to absorb high-frequency noise interference of the voltage output by the emitter follower composed of the first operational amplifier AK.

[0087] Preferably, the high-frequency capacitor is made of microwave dielectric material, which has extremely high stability and extremely low dielectric loss.

[0088] Preferably, the power synthesis circuit has simple structure, high reliability and flexible design; in order to prevent the transistor of a constant current source module from being damaged due to short circuit fault, the safety protection circuit of the superimposed constant current source power synthesizer is designed, so that when any independent constant current source module has short circuit fault, the power supply is automatically cut off for real-time safety protection.

[0089] As shown in Figure 3 , the safety protection circuit comprises a wire or circuit, a compound transistor and a voltage limiting protection circuit; the wire or circuit is connected with the voltage limiting protection circuit, and the voltage limiting protection circuit is connected with the compound transistor.

[0090] Preferably, the wire or circuit comprises N diodes D1-DN and a third resistor Ra.

[0091] The N diodes D1-DN are connected in parallel and connected with the voltage limiting protection circuit, and the connection node of the diodes and the voltage limiting protection circuit is grounded through the third resistor Ra.

[0092] The anodes of the N diodes D1-DN are respectively connected with the second resistors RD1-RDN of the N constant current source modules connected in parallel.

[0093] Preferably, the N diodes D1-DN are of the same type and have the same parameters.

[0094] Preferably, the diode is an electronic device made of semiconductor material (silicon, selenium, germanium, etc.); the diode has two electrodes, a positive electrode (anode) and a negative electrode (cathode); when a forward voltage is applied between the two electrodes of the diode, the diode is turned on, and when a reverse voltage is applied, the diode is turned off; the turn-on and turn-off of the diode are equivalent to the turn-on and turn-off of a switch.

[0095] Preferably, the diode has unidirectional conduction performance, and the current direction is from the anode to the cathode when the diode is turned on.

[0096] Preferably, the third resistor Ra is a current-limiting resistor, and the resistance value is selected to be in the order of kilo-ohms.

[0097] Preferably, the third resistor Ra is used to limit the current in the branch to prevent the series-connected components from being burned out due to excessive current, and the current-limiting resistor can also function as a voltage divider.

[0098] Preferably, the voltage limiting protection circuit comprises: a first zener diode DB and a fourth resistor Rb;

[0099] The cathode of the first zener diode DB is connected to one end of the fourth resistor Rb.

[0100] The anode of the first zener diode DB is grounded.

[0101] The cathodes of the N diodes D1-DN are connected in parallel and connected to the other end of the fourth resistor Rb.

[0102] Preferably, the fourth resistor Rb is a current limiting resistor when the first zener diode DB is reverse-biased.

[0103] Preferably, the resistance value of the fourth resistor Rb is selected to be in the order of tens of kilo-ohms.

[0104] Preferably, the first zener diode DB is a clamping diode, which protects the input voltage of the subsequent compound transistor from exceeding the safe voltage, which is the sum of the safe voltages of the input PN junctions of the two transistors, i.e. 1.8V.

[0105] Preferably, the voltage limiting value of the first zener diode DB is different from that of the second zener diode DA.

[0106] Preferably, the first zener diode DB and the fourth resistor Rb form a voltage limiting protection circuit, which keeps the voltage difference between the base and the emitter of the compound transistor within a safe range.

[0107] Preferably, when the voltage difference between the base and the emitter of the compound transistor exceeds the safe range, the first zener diode DB is reverse-biased, and the potential is clamped at the voltage limiting value.

[0108] Preferably, the compound transistor comprises: a second transistor TA and a third transistor TB.

[0109] The emitter of the second transistor TA is connected to the base of the third transistor TB.

[0110] The base of the second transistor TA is connected to one end of the fourth resistor Rb, and the connection node of the base of the second transistor TA and the fourth resistor Rb is connected to the cathode of the first zener diode DB.

[0111] The emitter of the third transistor TB is grounded.

[0112] Preferably, the second transistor TA is a front-stage transistor, which has a small power and a large current amplification factor, and functions to amplify the input current.

[0113] Preferably, the third transistor TB is a back-stage transistor, which has a small current amplification factor and a large power, and functions to output the amplified current.

[0114] The total current amplification factor of the composite transistor is preferably the product of the current amplification factors of the second transistor TA and the third transistor TB; the composite transistor has both a large current amplification factor and can output a large current.

[0115] The safety protection circuit preferably further comprises a second capacitor C2.

[0116] The base of the second transistor TA is connected to one end of a fourth resistor Rb, and the connection node of the base of the second transistor TA and the fourth resistor Rb is connected to the second capacitor C2 and then grounded.

[0117] The second capacitor C2 is preferably used to absorb high-frequency noise interference and instantaneous voltage spikes.

[0118] The first end of the relay J1 is connected to the collector of the second transistor TA and the collector of the third transistor TB, respectively.

[0119] The second end of the relay J1 is connected to the constant current source VC.

[0120] The third end of the relay J1 is connected to the power supply VCC.

[0121] Under normal circumstances, the relay J1 is in the attracted state, which connects the power supply VCC and the constant current source VC, and provides power supply to the superimposed constant current source power synthesizer.

[0122] The relay is preferably an electrical control device that can give a specified input quantity and maintain it for a long enough time to cause a predetermined step change in the controlled quantity in an electrical output circuit; when the input quantity decreases to a certain extent and maintains it for a long enough time, it returns to the initial state.

[0123] The relay preferably plays the roles of automatic adjustment, safety protection, and conversion circuit in the circuit.

[0124] The working principle of the safety protection circuit is as follows:

[0125] When a fault occurs in any stage of the N constant current source modules, the sampling voltage on the second resistor RDN in the faulty constant current source module suddenly increases, the potential of one of the V1-VN sampling voltages rises, a high level is generated through the corresponding collection of the N diodes D1-DN in the line or circuit, and the high level is input to the base of the composite transistor composed of the second transistor TA and the third transistor TB through the fourth resistor Rb. The composite transistor quickly saturates and turns on, driving the relay J1 connected to the collector, the relay J1 is disconnected, the power supply VCC is disconnected from the constant current source VC, the power supply of the power synthesizer circuit is cut off, and real-time safety protection of the overall circuit is realized.

[0126] Preferably, the application provides an independent superimposed constant current source power synthesizer, which adopts independent constant current source modules to perform balanced superimposed synthesis, the currents of each constant current source module are uniform and consistent, and large current can be balanced synthesized; a line or circuit is used as a safety protection circuit, and a composite transistor provides large driving current to ensure reliable operation of the relay; all circuits are realized by pure hardware circuits, have fast response rate, simple circuit structure, high reliability, and can be widely applied to systems of large power constant current source driving; the number of constant current source modules is determined according to the size of the total current, has strong expansibility, and appropriately increases redundancy to ensure the safety and reliability of the overall constant current source; by using the above technical scheme, the key technical problems in the design of the large power constant current source are solved, the balanced linear superposition meets the demand of outputting large current, and at the same time, the design process is modularized, standardized and serialized, has strong expansibility, and can be applied to various application occasions of large power constant current source.

[0127] The various embodiments in the specification are described in a progressive manner, and each embodiment focuses on the difference from other embodiments, and the same or similar parts between the various embodiments can be referred to each other. For the device disclosed by the embodiments, since it corresponds to the method disclosed by the embodiments, the description is relatively simple, and the related parts can be referred to the method part.

[0128] The above description of the disclosed embodiments enables a person skilled in the art to implement or use the application. Various modifications to the embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the application. Therefore, the application will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An independent superimposed constant current source power combiner, characterized in that, include: Power combining circuit and safety protection circuit; The power combining circuit includes: a first operational amplifier and N constant current source modules; the N constant current source modules are connected in parallel and then connected to the first operational amplifier; N is a positive integer greater than 1; The constant current source module includes: a second operational amplifier, a first transistor, a first resistor, and a second resistor; The output of the second operational amplifier is connected to the base of the first transistor; The inverting input of the second operational amplifier and the emitter of the first transistor are connected to a second resistor and then grounded. The collectors of N first transistors are connected in parallel and then connected to a constant current source through a load resistor; The N non-inverting input terminals of the second operational amplifiers are connected in parallel with the first resistor; The total output current IM of the superimposed constant current source power combiner is: IM = N * IN, where IN represents the output current of the independent constant current source module; The safety protection circuit includes: a line or circuit, a composite transistor, and a voltage limiting protection circuit; the line or circuit is connected to the voltage limiting protection circuit, and the voltage limiting protection circuit is connected to the composite transistor; Each of the N constant current source modules is connected to the line or circuit; The line or circuit includes: N diodes and a third resistor; N diodes are connected in parallel and then connected to the voltage limiting protection circuit, and the connection node between the diodes and the voltage limiting protection circuit is grounded through the third resistor; The anodes of the N diodes are respectively connected to the second resistors in the N parallel constant current source modules.

2. The independent superimposed constant current source power combiner according to claim 1, characterized in that, The N parallel constant current source modules all have the same circuit structure, and the first operational amplifier, the first transistor, the first resistor, and the second resistor in each constant current source module are all the same.

3. The independent superimposed constant current source power combiner according to claim 1, characterized in that, The voltage limiting protection circuit includes: a first Zener diode and a fourth resistor; The cathode of the first Zener diode is connected to one end of the fourth resistor; The anode of the first Zener diode is grounded; The cathodes of the N diodes are connected in parallel and then connected to the other end of the fourth resistor.

4. The independent superimposed constant current source power combiner according to claim 3, characterized in that, The composite transistor includes: a second transistor and a third transistor; The emitter of the second transistor is connected to the base of the third transistor; The base of the second transistor is connected to one end of the fourth resistor, and the connection node between the base of the second transistor and the fourth resistor is connected to the cathode of the first Zener diode. The emitter of the third transistor is grounded.

5. The independent superimposed constant current source power combiner according to claim 1, characterized in that, The output terminal of the first operational amplifier is connected to the first resistor in one of the N constant current source modules; the inverting input terminal of the first operational amplifier is connected to the output terminal of the first operational amplifier; and the non-inverting input terminal of the first operational amplifier is connected to the regulating power supply.

6. The independent superimposed constant current source power combiner according to claim 5, characterized in that, The power combining circuit further includes: a second Zener diode and a first capacitor; The connection node between the output terminal of the first operational amplifier and the N first resistors is connected to the cathode of the second Zener diode. The anode of the second Zener diode is grounded; The connection point between the output terminal of the first operational amplifier and the N first resistors is connected to the first capacitor and then grounded.

7. The independent superimposed constant current source power combiner according to claim 4, characterized in that, The safety protection circuit also includes: a second capacitor; The base of the second transistor is connected to one end of the fourth resistor, and the connection node between the base of the second transistor and the fourth resistor is connected to the second capacitor and then grounded.

8. The independent superimposed constant current source power combiner according to claim 4, characterized in that, The safety protection circuit also includes: a relay; The first terminal of the relay is connected to the collector of the second transistor and the collector of the third transistor, respectively. The second terminal of the relay is connected to the constant current source; The third terminal of the relay is connected to the power supply.

Images