An equivalent load power stabilization control circuit based on constant current source

Abstract

The invention discloses an equivalent load power stabilization control circuit based on a constant current source, comprising a first and a second voltage stabilizing diode, a first and a second current limiting resistor and a first and a second electronic switch; the cathode of the first voltage stabilizing diode is connected to the anode of the constant current source, the anode is connected to the first current limiting resistor and then connected to the cathode of the constant current source; the first end of the first electronic switch is connected to the anode of the first voltage stabilizing diode, the second end is connected to the cathode of the constant current source, and the third end is connected to the anode of the constant current source; the cathode of the second voltage stabilizing diode is connected to the anode of the constant current source, the anode is connected to the second current limiting resistor and then connected to the cathode of the constant current source; the first end of the second electronic switch is connected to the anode of the second voltage stabilizing diode, the second end is connected to the cathode of the constant current source, and the third end is connected to the cathode of the constant current source as an output port for connecting an external load; the invention can change its own power loss according to the change of the load, ensure that the power supply power of the constant current source remains basically unchanged, and has the advantages of stability, reliability, fewer peripheral components, etc.

Description

Technical Field

[0001] The present invention belongs to the technical field of power electronics, and more specifically, relates to an equivalent load power stabilization control circuit based on a constant current source. Background Art

[0002] The existing DC power supply system usually adopts constant voltage power supply. However, with the development of science and technology and the expansion of new power supply technology, especially in the future underwater information system and network, the constant current power supply system will show its unique advantages. However, in the constant current source power supply network, once the load impedance changes or the load fails, it will cause an impact on the power supply system, affecting the normal operation of the power supply system and even affecting other electrical equipment.

[0003] Therefore, in this type of power supply system, it is inevitable to use an equivalent load stabilization circuit, that is, after adding this circuit, when the load changes, its equivalent load remains stable or basically unchanged relative to the constant current power supply network. Reduce the impact of load fluctuations or failures on the main power supply system, and at the same time ensure that the normal operation of the power supply system and the normal power supply of other electrical equipment are not affected when replacing or repairing load equipment. In addition, for underwater environments, avoid the impact caused by load line interruption, water ingress, etc. This requires the design of a power control circuit to complete this function, and the present invention is based on this background. Summary of the invention

[0004] In response to at least one defect or improvement need in the prior art, the present invention provides an equivalent load power stabilization control circuit based on a constant current source, which is arranged between the constant current source and the load, and can change the power loss of the control circuit itself according to the change of the load resistance, thereby ensuring that for the constant current source, its power supply power remains basically unchanged or the change is controlled within a very small range; reducing the impact on the power supply system trunk line when the load changes or failures occur, and at the same time solving the problem of the difficulty of live maintenance and replacement of underwater constant current power supply equipment.

[0005] To achieve the above object, according to one aspect of the present invention, there is provided an equivalent load power stabilization control circuit based on a constant current source, which includes a first voltage stabilizing diode, a second voltage stabilizing diode, a first current limiting resistor, a second current limiting resistor, a first electronic switch and a second electronic switch;

[0006] The cathode of the first voltage zener diode is connected to the anode of the constant current source, the anode is connected to the first current limiting resistor and then connected to the cathode of the constant current source; the first end of the first electronic switch is connected to the anode of the first voltage zener diode, the second end is connected to the cathode of the constant current source, and the third end is connected to the anode of the constant current source;

[0007] The cathode of the second voltage stabilizing diode is connected to the anode of the constant current source, the anode is connected to the second current limiting resistor and then connected to the cathode of the constant current source; the first end of the second electronic switch is connected to the anode of the second voltage stabilizing diode, the second end is connected to the cathode of the constant current source, and the third end is connected to the cathode of the constant current source as an output port for connecting an external load;

[0008] The switching state of the first electronic switch is controlled by the first zener diode, and the switching state of the second electronic switch is controlled by the second zener diode, so that the power loss borne by the first and second electronic switches changes in response to the equivalent impedance of the load, so as to control the power supply of the constant current source within a desired range.

[0009] Preferably, the above-mentioned equivalent load power stabilization control circuit also includes a first preset resistor arranged between the third end of the first electronic switch and the positive electrode of the constant current source.

[0010] Preferably, the above-mentioned equivalent load power stabilization control circuit also includes a second preset resistor arranged in parallel with the second end and the third end of the second electronic switch.

[0011] Preferably, in the above-mentioned equivalent load power stabilization control circuit, the resistance value of the first preset resistor and / or the second preset resistor is equal to the rated impedance value of the control circuit.

[0012] Preferably, in the above-mentioned equivalent load power stabilization control circuit, when the actual impedance of the load is less than or equal to the rated impedance value of the control circuit, the first electronic switch is turned off, the second electronic switch is turned on, the output port of the control circuit maintains a constant current output and its output current value is equal to the output current value of the constant current source.

[0013] Preferably, in the above-mentioned equivalent load power stabilization control circuit, when the actual impedance of the load is greater than the rated impedance value of the control circuit, the first and second electronic switches are both turned on, the output port of the control circuit maintains a constant voltage output and its output voltage value is equal to the output voltage value of the constant current source.

[0014] Preferably, in the above-mentioned equivalent load power stabilization control circuit, the rated impedance value of the control circuit is the ratio between the voltage stabilization value of the second voltage stabilizing diode and the output current value of the constant current source.

[0015] Preferably, in the above-mentioned equivalent load power stabilization control circuit, the voltage stabilization value of the first voltage stabilizing diode is 3 to 5V higher than that of the second voltage stabilizing diode.

[0016] Preferably, in the above-mentioned equivalent load power stabilization control circuit, the maximum power loss borne by the first electronic switch or the second electronic switch is not greater than 2 / 3 of its own maximum allowable dissipation power.

[0017] Preferably, in the above-mentioned equivalent load power stabilization control circuit, the first electronic switch or the second electronic switch is selected from any one of a bipolar transistor, a field effect transistor, and an IGBT.

[0018] In general, the above technical solutions conceived by the present invention can achieve the following beneficial effects compared with the prior art:

[0019] (1) The equivalent load power stabilization control circuit provided by the present invention utilizes the voltage stabilizing diodes Z1 and Z2 to control the switching states of the switch tubes M1 and M2, and ingeniously utilizes the output characteristics of the switch tubes M1 and M2 in the non-saturation zone and the saturation zone, so that the power loss borne by M1 and M2 changes with the equivalent impedance of the load, thereby achieving the purpose of controlling the total power loss and controlling the change of the total power supply of the constant current source within a very small range; it has the advantages of being simple and practical, stable and reliable, having few peripheral components, and being easy to promote and apply.

[0020] (2) The equivalent load power stabilization control circuit provided by the present invention increases the preset resistance R J1 With R J2 The optimized circuit formed later reduces the power loss of the switch tubes M1 and M2. The maximum power loss borne by the electronic switches M1 and M2 is 1 / 4 of the power supply of the constant current source, which is 3 / 4 less than that of the basic circuit, and effectively reduces the stress of M1 and M2. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a basic topological structure diagram of the equivalent load power stabilization control circuit provided by an embodiment of the present invention;

[0022] Figure 2 It is an optimized topological structure diagram of the equivalent load power stabilization control circuit provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0024] Embodiment 1

[0025] Figure 1 The basic topology diagram of the equivalent load power stabilization control circuit provided in this embodiment is as follows: Figure 1As shown, the control circuit includes voltage-stabilizing diodes Z1, Z2, current-limiting resistors R1, R2 and electronic switches M1, M2; wherein the electronic switches M1, M2 may be bipolar transistors, field-effect transistors or IGBTs. This embodiment is described by taking the electronic switches M1, M2 both using N-channel enhancement-type MOS field-effect transistors as an example.

[0026] In this control circuit, the cathode of the voltage zener diode Z1 is connected to the anode of the constant current source, the anode of the voltage zener diode Z1 is connected to the current limiting resistor R1 and then connected to the cathode of the constant current source; the gate of the electronic switch M1 is connected to the anode of the voltage zener diode Z1, the drain is connected to the anode of the constant current source, and the source is connected to the cathode of the constant current source; the cathode of the voltage zener diode Z2 is connected to the anode of the constant current source, the anode of the voltage zener diode Z2 is connected to the current limiting resistor R2 and then connected to the cathode of the constant current source; the gate of the electronic switch M2 is connected to the anode of the voltage zener diode Z2, the source is connected to the cathode of the constant current source, and the drain of the electronic switch M2 and the cathode of the constant current source serve as output ports for connecting an external load.

[0027] The innovation of this control circuit is to use the voltage zener diodes Z1 and Z2 to control the switching state of the electronic switches M1 and M2, and to cleverly use the output characteristics of the non-saturated and saturated regions of the electronic switches M1 and M2 so that the power loss borne by the electronic switches M1 and M2 changes with the change of the equivalent impedance of the load, thereby achieving the purpose of controlling the total power loss and making the total power supply power of the external constant current source basically unchanged or controlling the change within a very small range.

[0028] See also Figure 1 The electronic switches M1 and M2 are the core components of this embodiment, and have the function of controlling the magnitude of the current flowing through the path and bearing the power loss.

[0029] <1> When the actual load impedance is less than or equal to the rated impedance value (including the load impedance is zero, that is, the load has a short circuit fault), the electronic switch M2 is turned on and works in the saturation region. The control circuit outputs a constant current to the load and the current flowing through the load and the electronic switch M2 is equal to the output current of the external constant current source. That is, the output current I load With input current I in The relationship is as follows:

[0030] I load =I in (1)

[0031] And in this state, the output voltage value of the external constant current source remains basically unchanged, and its value is:

[0032] V in =V Z2 +V GS2 ≈V Z2 +V T (2)

[0033] In formula (2), V in is the output voltage value of the external constant current source, V Z2 is the voltage value of the Zener diode Z2, V GS2 is the voltage difference between the gate and source of the electronic switch M2, V T is the turn-on voltage of the electronic switch M2.

[0034] In this state, the power supply of the external constant current source remains basically unchanged, and its value is:

[0035] P in =V in I in ≈(V Z2 +V T )I in (3)

[0036] In formula (3), P in It is the power supply of external constant current source.

[0037] <2> When the actual load impedance is greater than the rated impedance value (including when the load impedance is infinite, i.e., when the load has an open circuit fault), the electronic switch M1 is turned on and operates in the saturation region, and the electronic switch M2 is turned on and operates in the non-saturation region. The control circuit outputs a constant voltage to the load and the output voltage value is equal to the output voltage value of the external constant current source, which is:

[0038] V load =V in =V Z1 +V GS1 ≈V Z1 +V T (4)

[0039] In formula (4), V load is the output voltage of this circuit, V Z1 is the voltage value of the Zener diode Z1, V GS1 is the voltage difference between the gate and source of the electronic switch M1.

[0040] In this state, the power supply of the external constant current source remains basically unchanged, and its value is:

[0041] P in =V in I in ≈(V Z1 +V T )I in (5)

[0042] In this control circuit, V Z1 V Z2 3~5V higher is enough, and the rated impedance of the load is:

[0043]

[0044] In formula (6), R e is the rated impedance of the load.

[0045] The output voltage variation range of the external constant current source in the two states is ΔV in =V Z1 -V Z2 , the power supply range is ΔP in =(V Z1 -V Z2 )I in , the total power supply power of the external constant current source remains basically unchanged or the change is controlled within a very small range.

[0046] Specifically, the working process of this control circuit is as follows:

[0047] <1> When the actual load impedance is less than or equal to the rated impedance value, the current in the circuit of the present invention has no path at the initial moment, and the external constant current source outputs a voltage V in Rising, when it rises to V in =V Z2 +V T When the electronic switch M2 starts to conduct, the voltage V between the gate and source of M2 GS2 for:

[0048] V GS2 =V in -V Z2 (7)

[0049] When M2 is turned on, the voltage between its drain and source is:

[0050] V DS2 =V in -I in R load (8)

[0051] Because I in R load ≤V Z2 , so V DS2 ≥V GS2 , satisfying V DS ≥V GS -V T The boundary condition of the electronic switch M2 is that it works in the saturation region, and the current I between its drain and source is DS2 The gate-source voltage V GS2 Decision, V GS2 Small changes will cause I DS2 Large changes, accompanied by the external constant current source output voltage V in The voltage V between the gate and source of the electronic switch M2 increases.GS2 is also rising, and at the same time the current I DS2 is also rising, when I DS2 When the following conditions are met, the voltage V in and voltage V GS2 No longer rising, reaching a steady state:

[0052] I DS2 =I in (9)

[0053] In this steady state, the control circuit has a constant current output for the load and the output current value is equal to the output current value of the external constant current source, I load =I in At this time, the output voltage value of the external constant current source remains basically unchanged, V in =V Z2 +V GS2 ≈V Z2 +V T ; The power supply of the external constant current source remains basically unchanged, P in =V in I in ≈(V Z1 +V T )I in .

[0054] <2> When the actual load impedance is greater than the rated impedance, the load voltage will be greater than the stable voltage V of the Zener diode Z2. Z2 , constant current source input voltage V in When the actual load impedance is less than or equal to the rated impedance, the voltage V between the gate and source of the electronic switch M2 increases. GS2 Similarly, when the actual load impedance is slightly greater than the rated impedance, that is, when the electronic switch M1 is not turned on, the current I flowing through the load load , the current I between the drain and source of the electronic switch M2 DS2 No change, still maintain I load =I DS2 =I in , voltage V GS2 No longer determines the drain-source current I DS2 The size of V GS2 The drain-source voltage V DS2 No longer satisfied with V DS ≥V GS -V T The electronic switch M2 works in the non-saturated region. The external constant current source output voltage V in With R load increases with the increase of in When the following relationship is met, the electronic switch M1 is turned on to shunt the current of the external constant current source:

[0055] V GS1 =V in -V Z1 >V T (10)

[0056] When the electronic switch M1 is turned on, the voltage between its drain and source is V DS1 Equal to the external constant current source output voltage V in , satisfying V DS ≥V GS -V T boundary conditions, so the electronic switch M1 operates in the saturation region, and the gate-source voltage V GS1 Determines the drain-source current I flowing through M1 DS1 , and V GS1 Small changes will cause I DS1 Large changes, when I DS1 The current I between the drain and source of the electronic switch M2 DS2 When the following relationship is satisfied, the circuit enters a new steady state, and the constant current source output voltage V in Basically unchanged.

[0057] I DS1 +I DS2 =I in (11)

[0058] The current I flowing through the electronic switch M2 in this steady state DS2 is equal to the load current, which is:

[0059]

[0060] As analyzed above, the electronic switch M2 works in the non-saturated region, and its on-state resistance increases with V GS2 increases and decreases; therefore, the voltage V between the drain and source of M2 DS2 Very small, compared to V in can be ignored, so:

[0061]

[0062] In this steady state, the control circuit provides a constant voltage output to the load and the output voltage value is equal to the output voltage value of the external constant current source, V load =V in -V DS2 ≈V in , the output voltage value of the external constant current source remains basically unchanged, V in =V Z1 +V GS1 ≈V Z1 +V T; The power supply of the external constant current source remains basically unchanged, P in =V in I in ≈(V Z1 +V T )I in .

[0063] When the load is short-circuited, the electronic switch M2 takes on the power loss P M2 Maximum, equal to the power supply of the external constant current source; when the load has an open circuit fault, the power loss P borne by the electronic switch M1 M1 Maximum, equal to the power supply of the external constant current source. Therefore, the circuit of the present invention should work under the premise that the maximum power loss borne by the electronic switch is less than its maximum allowable dissipation power. The maximum allowable dissipation power of the electronic switch decreases with the increase of the working temperature of the electronic switch. In order to ensure sufficient margin, the maximum power loss borne by the electronic switch is about 2 / 3 of the maximum allowable dissipation power of the electronic switch, and the circuit voltage regulator parameters and rated load impedance are designed accordingly.

[0064] In general, the control circuit provided in this embodiment has a rated load impedance value, that is, the maximum effective load value of the constant current output guaranteed by the circuit. When the actual impedance of the load is less than or equal to the rated impedance value (including the load impedance is zero, that is, the load has a short circuit fault), the control circuit is a constant current output for the load and the output current value is equal to the output current value of the external constant current source. At this time, the electronic switch M1 is turned off, the electronic switch M2 is turned on, and the power loss is borne by the load and the electronic switch M2. When the actual impedance of the load is equal to the rated impedance value, the power loss borne by the electronic switch M2 is very small (negligible), and the loss power borne by the load is basically equal to the power supply power of the constant current source; when the actual impedance of the load is greater than the rated impedance value (including the load impedance is infinite, that is, the load has an open circuit fault), the control circuit is a constant voltage output for the load and the output voltage value is equal to the output voltage value of the external constant current source. At this time, the electronic switches M1 and M2 are both turned on, and the power loss is borne by the load, the electronic switches M1, and M2. Because the drain-source voltage of the electronic switch M2 is very small, its power loss is very small (negligible).

[0065] In the two states, the output voltage variation range of the external constant current source is the difference between the voltage regulation values ​​of the Zener diodes Z1 and Z2, and the output power variation range of the external constant current source is the product of the difference between the voltage regulation values ​​of the Zener diodes Z1 and Z2 and the output current of the external constant current source.

[0066] The present invention can keep the power supply power basically unchanged or control the change within a very small range when the load of the constant current power supply mode changes over a large range (including load short circuit and open circuit failure), and has the advantages of simplicity, high efficiency, stability and reliability.

[0067] Embodiment 2

[0068] Figure 2 The optimized topological structure diagram of the equivalent load power stabilization control circuit provided in this embodiment is as follows: Figure 2 As shown, the circuit structure of this embodiment is basically the same as that of the first embodiment, and the main difference is that: in order to reduce the power loss of the electronic switch, and thus improve the output power of the external constant current source and the rated load impedance value of the control circuit of the present invention, a preset resistor R is preferably connected in parallel between the drain and source of the electronic switch M2. J2 , the source of the electronic switch M2 is connected to the negative pole of the power supply, and the drain of the electronic switch M2 and the positive pole of the power supply are used as output ports to connect external loads; or, a preset resistor R is connected in series between the drain of the electronic switch M1 and the positive pole of the power supply. J1 , that is, connect the drain of the electronic switch M1 in series with a preset resistor R J1 Further preferably, a preset resistor R is connected in parallel between the drain and source of the electronic switch M2. J2 , and a preset resistor R is connected in series between the drain of the electronic switch M1 and the positive electrode of the power supply J1 ; The above preset resistance R J1 With R J2 Equal to the rated load impedance R e The working principle of the control circuit provided in this embodiment is the same as that of the first embodiment, and will not be described in detail here.

[0069] In the optimized circuit provided in this embodiment, when the actual load impedance is greater than the rated impedance value, the voltage V between the drain and source of the electronic switch M2 is DS2 is very small, so it bears the power loss P M2 The maximum value occurs when the actual load impedance is less than or equal to the rated impedance value; the power loss P M2 The relationship is:

[0070] P M2 =I DS2 V DS2 (14)

[0071] In formula (14), I DS2 is the current value between the drain and source of the electronic switch M2, which satisfies the following relationship:

[0072]

[0073] Substituting (15) into (14) we obtain:

[0074]

[0075] From this we can get the power loss P M2 Yes V DS2 The quadratic function, P M2When the maximum value is achieved, V DS2 The values ​​are:

[0076]

[0077] Power loss P M2 The maximum value is:

[0078]

[0079] In formula (18), I in 2 R J2 It is approximately the power supply of the external constant current source when the load impedance is the rated impedance. Therefore, the maximum power loss of the electronic switch M2 in the optimized control circuit is 1 / 4 of the power supply of the constant current source, which is 3 / 4 less than that of the basic circuit.

[0080] Similarly, the maximum power loss P borne by the electronic switch M1 is M1 It occurs when the actual load impedance is greater than the rated impedance value, and the relationship is:

[0081] P M1 =I DS1 V DS1 (19)

[0082] In formula (19), I DS1 is the current between the drain and source of the electronic switch M1, V DS1 is the voltage between the drain and source of the electronic switch M1, and the relationship is:

[0083] V DS1 =V in -I DS1 R J1 (20)

[0084] Substituting (20) into (19), we obtain:

[0085] P M1 =I DS1 V in -I DS1 2 R J1 (twenty one)

[0086] From this we can get the power loss P M1 isI DS1 The quadratic function, P M1 When the maximum value is obtained, I DS1 The values ​​are:

[0087]

[0088] Power loss P M1 The maximum value is:

[0089]

[0090] In formula (23), It is approximately the power supply power of the external constant current source when the load impedance is the rated impedance. Therefore, the maximum power loss borne by the electronic switch M1 in the optimized control circuit is 1 / 4 of the power supply power of the constant current source, which is 3 / 4 less than that of the basic circuit.

[0091] Under the premise of ensuring that the maximum power loss of the electronic switch is about 2 / 3 of the maximum allowable power dissipation of the electronic switch, a preset resistor R is added to the basic circuit provided in the first embodiment. J1 With R J2 The optimized circuit formed later can adapt to higher constant current source power supply and has a higher rated load impedance value, further broadening the application scope of the present invention.

[0092] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. An equivalent load power stabilization control circuit based on a constant current source, characterized in that: It includes a first voltage-stabilizing diode, a second voltage-stabilizing diode, a first current-limiting resistor, a second current-limiting resistor, a first electronic switch, a second electronic switch and a first preset resistor, wherein the first preset resistor is arranged between the third end of the first electronic switch and the positive electrode of the constant current source; The cathode of the first voltage zener diode is connected to the anode of the constant current source, the anode is connected to the first current limiting resistor and then connected to the cathode of the constant current source; the first end of the first electronic switch is connected to the anode of the first voltage zener diode, the second end is connected to the cathode of the constant current source, and the third end is connected to the anode of the constant current source; The cathode of the second voltage stabilizing diode is connected to the anode of the constant current source, the anode is connected to the second current limiting resistor and then connected to the cathode of the constant current source; the first end of the second electronic switch is connected to the anode of the second voltage stabilizing diode, the second end is connected to the cathode of the constant current source, and the third end is connected to the cathode of the constant current source as an output port for connecting an external load; The switching state of the first electronic switch is controlled by the first voltage zener diode, and the switching state of the second electronic switch is controlled by the second voltage zener diode, so that the power loss borne by the first and second electronic switches changes in response to the equivalent impedance of the load, so as to control the power supply of the constant current source within a desired range; The first electronic switch or the second electronic switch is selected from any one of a bipolar transistor, a field effect transistor, and an IGBT.

2. The equivalent load power stabilization control circuit according to claim 1, characterized in that: It also includes a second preset resistor connected in parallel with the second end and the third end of the second electronic switch.

3. The equivalent load power stabilization control circuit according to claim 2, characterized in that: The resistance value of the first preset resistor and / or the second preset resistor is equal to the rated impedance value of the control circuit.

4. The equivalent load power stabilization control circuit according to claim 1, characterized in that: When the actual impedance of the load is less than or equal to the rated impedance value of the control circuit, the first electronic switch is turned off, the second electronic switch is turned on, and the output port of the control circuit maintains a constant current output and its output current value is equal to the output current value of the constant current source.

5. The equivalent load power stabilization control circuit according to claim 1, characterized in that: When the actual impedance of the load is greater than the rated impedance value of the control circuit, the first and second electronic switches are both turned on, the output port of the control circuit maintains a constant voltage output and its output voltage value is equal to the output voltage value of the constant current source.

6. The equivalent load power stabilization control circuit according to any one of claims 3 to 5, characterized in that: The rated impedance value of the control circuit is the ratio between the voltage stabilization value of the second voltage stabilizing diode and the output current value of the constant current source.

7. The equivalent load power stabilization control circuit according to claim 1, characterized in that: The voltage stabilization value of the first voltage stabilizing diode is 3-5V higher than that of the second voltage stabilizing diode.

8. The equivalent load power stabilization control circuit according to claim 1, characterized in that: The maximum power loss borne by the first electronic switch or the second electronic switch is no greater than 2 / 3 of its own maximum allowable dissipated power.

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