Constant current control circuit, control system and electrical equipment

Abstract

The invention discloses a constant current control circuit, a control system and electrical equipment, and belongs to the field of constant current control. The constant current control circuit comprises a stabilized voltage supply, an enabling unit, a negative feedback comparison amplification unit, a driving tube module unit and a sampling unit. The voltage-stabilized power supply supplies power to the load unit; when the driving tube module unit is conducted, the load unit is powered on, the sampling unit can obtain current flowing through the load and feed the current back to the negative feedback comparison amplification unit, and the negative feedback comparison amplification unit controls whether the driving tube module unit is conducted or not. The enabling unit controls whether the negative feedback comparison amplification unit can control the driving module unit or not. According to the virtual short, the voltage fed back by the sampling unit is the same as the voltage of the input signal; therefore, when the values of other components are determined, the current finally flowing through the load is only related to the voltage of the input signal. Therefore, the current flowing through the load unit can be ensured to be unchanged as long as the voltage of the input signal is ensured to be unchanged.

Description

Technical Field

[0001] The present application relates to the field of constant current control technology, and in particular, to a constant current control circuit, a control system and an electrical device. Background Art

[0002] In some special occasions, it is necessary to use constant current to drive devices such as semiconductor lasers LD, light-emitting diodes LED, and UV curing lamps.

[0003] For example, the characteristic curve (PI characteristic curve) of the relationship between the output power and current (optical-electrical parameters) of a typical LD ​​is as follows: Figure 1 As shown. When the laser is forward biased and injected with current, there is light output. At the beginning, the output light efficiency is very low, that is, the slope of the curve is very small. This stage is the spontaneous radiation luminescence stage. After the injection current increases to a certain value Iw, the luminescence efficiency begins to increase, and the PI curve begins to bend upward into a straight line, indicating that stimulated radiation luminescence begins to work and gradually increases in proportion, and carrier recombination is converted into stimulated light radiation, that is, when the particle number inversion reaches the point where the gain obtained by the photon in the cavity is equal to the loss suffered, the photon can obtain net gain and oscillate and emit in the cavity. After that, the light output power rises steeply with the current. When the current reaches Im (not shown in the figure), the light output function will reach infinity and the LD will be damaged.

[0004] Therefore, if LD is to emit light normally and stably, a stable current needs to be injected, and the current needs to be a stable value between Iw and Im. The smaller the current fluctuation, the more stable the light emission.

[0005] The existing constant current control circuit is relatively conventional, but there is currently no better solution for scenarios with high requirements such as current stability. Summary of the invention

[0006] In order to overcome the shortcomings of the prior art, the present application provides a constant current control circuit, a control system and electrical equipment to solve the problem that the existing constant current control circuit is relatively conventional, but has high requirements for current stability and other scenarios, and there is currently no better solution.

[0007] The technical solution adopted by this application to solve its technical problem is:

[0008] In a first aspect, a constant current control circuit is provided, comprising: a voltage-stabilized power supply, an enabling unit, a negative feedback comparison amplifier unit, a driving tube module unit and a sampling unit;

[0009] The voltage-stabilized power supply is connected to the load unit to supply power to the load unit;

[0010] The negative feedback comparison amplification unit comprises a negative feedback amplifier, a positive input terminal of the negative feedback amplifier is grounded, an inverting input terminal of the negative feedback amplifier is connected to an input signal, and an output terminal of the negative feedback amplifier is connected to an inverting input terminal of the negative feedback amplifier; the output terminal of the negative feedback amplifier is connected to a control terminal of the driving tube module unit;

[0011] The enabling unit is connected to the load unit and the inverting input terminal of the negative feedback amplifier respectively;

[0012] The load unit is connected to the input end of the driving tube module unit, and the driving tube module unit is connected to the inverting input end of the negative feedback amplifier through the sampling unit.

[0013] Further, the enabling unit includes an enabling control unit;

[0014] The enabling control unit includes a first switch;

[0015] One end of the first switch is connected to an enable signal, and the other end of the first switch is connected to the inverting input end of the negative feedback amplifier through a first diode;

[0016] When the first switch is in a first state, the first diode is conductive, and when the first switch is in a second state, the first diode is non-conductive.

[0017] Further, the enabling unit includes an enabling indicating unit;

[0018] The enable indication unit includes a second diode, and the second diode is a light emitting diode;

[0019] The other end of the first switch is also grounded through the second diode;

[0020] When the first switch is in a first state, the second diode is conductive, and when the first switch is in a second state, the second diode is non-conductive.

[0021] Furthermore, it also includes a load protection unit;

[0022] The load protection unit is connected to the load unit and is used to protect the load unit.

[0023] Further, the load protection unit includes a short circuit protection unit and / or a reverse connection protection unit;

[0024] The short circuit protection unit is connected to the enabling unit;

[0025] The short circuit protection unit includes a second switch;

[0026] The second switch is connected in parallel at both ends of the load unit;

[0027] The reverse connection protection unit includes a fourth diode;

[0028] The fourth diode is connected in parallel across the load unit.

[0029] Furthermore, the load protection unit also includes a delayed start unit;

[0030] The delayed start unit includes a second capacitor;

[0031] The second capacitor is connected in parallel across the load unit.

[0032] Furthermore, it also includes: a current limiting protection circuit unit;

[0033] The current limiting protection circuit unit includes a comparison amplifier;

[0034] The first input terminal of the comparison amplifier is connected to the sampling unit; the second input terminal of the comparison amplifier is connected to the current limiting signal; and the output terminal of the comparison amplifier is connected to the inverting input terminal of the negative feedback amplifier.

[0035] Furthermore, the current limiting signal is connected to the second input terminal of the comparison amplifier through a second follower amplifier.

[0036] Furthermore, the sampling unit is connected to the first input terminal of the comparison amplifier through a third follower amplifier.

[0037] Furthermore, it also includes: a sampling and amplification unit;

[0038] The sampling and amplifying unit is connected to the sampling unit and is used to amplify the sampling voltage of the sampling unit.

[0039] Further, the input end of the driving tube module unit is connected to the inverting input end of the negative feedback amplifier through the sampling unit;

[0040] Alternatively, the output end of the driving tube module unit is connected to the inverting input end of the negative feedback amplifier through the sampling unit.

[0041] Further, it also includes: a first follower amplifier;

[0042] The first follower amplifier is arranged between the input signal and the inverting input terminal of the negative feedback amplifier.

[0043] Further, it also includes: a first amplifier;

[0044] The first amplifier is arranged between the input signal and an inverting input terminal of the negative feedback amplifier.

[0045] Furthermore, the driving pipe module unit is any one of the following:

[0046] MOS tubes, triodes, IGBTs and Darlington tubes.

[0047] In a second aspect, a control system is provided, comprising:

[0048] The above constant current control circuit;

[0049] A load unit connected to the constant current control circuit.

[0050] In a third aspect, an electrical device is provided, comprising the above-mentioned control system.

[0051] Beneficial effects:

[0052] The technical solution of the present application provides a constant current control circuit, a control system and an electrical device. The constant current control circuit includes a voltage-stabilized power supply, an enabling unit, a negative feedback comparison amplifier unit, a driving tube module unit and a sampling unit; the voltage-stabilized power supply supplies power to the load unit; when the driving tube module unit is turned on, the load unit is energized, and the sampling unit can obtain the current flowing through the load and then feed it back to the negative feedback comparison amplifier unit, and the negative feedback comparison amplifier unit controls whether the driving tube module unit is turned on. The enabling unit controls whether the negative feedback comparison amplifier unit can control the driving module unit. According to the virtual short, the voltage fed back by the sampling unit is the same as the voltage of the input signal; therefore, when the values ​​of other components are determined, the current that ultimately flows through the load is only related to the voltage of the input signal. In this way, as long as the voltage of the input signal is ensured to remain unchanged, the current flowing through the load unit can be guaranteed to remain unchanged. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0054] Figure 1 is a characteristic curve of the relationship between the output power and current of a typical LD ​​provided in an embodiment of the present application;

[0055] Figure 2 This is a schematic diagram of a constant current control circuit structure provided in an embodiment of the present application;

[0056] Figure 3 This is a schematic diagram of a specific constant current control circuit structure provided in an embodiment of the present application;

[0057] Figure 4 is a specific constant current control circuit schematic provided in an embodiment of the present application;

[0058] Figure 5 This is a control circuit schematic diagram of an enabling unit provided in an embodiment of the present application. Description of the drawings:

[0060] DAC1-input signal, U1-first follower amplifier, R1-first resistor, U2-first amplifier, R3-third resistor, R4-fourth resistor, U3-negative feedback amplifier, R5-fifth resistor, Q1-driving tube, LD-load unit, D1-first diode, D2-second diode, R7-seventh resistor, J1-first switch, C3-third capacitor, D4-fourth diode, C2-second capacitor, J2-second switch, R6-sixth resistor, R8-eighth resistor, R9-ninth resistor, U4-sampling amplifier unit, R11-eleventh resistor, R12-twelfth resistor, U5-third follower amplifier, R13-thirteenth resistor, R14-fourteenth resistor, R15-fifteenth resistor, U6-second follower amplifier, DAC2-current limiting signal, U7-comparison amplifier, C4-fourth capacitor, D5-fifteenth diode. DETAILED DESCRIPTION

[0061] In order to make the purpose, technical scheme and advantages of the present application clearer, the technical scheme of the present application is described in detail below in conjunction with the accompanying drawings and embodiments. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other implementation methods obtained by ordinary technicians in the field without making creative work belong to the scope of protection of the present application.

[0062] Reference Figure 2 , the embodiment of the present application provides a constant current control circuit, including: a voltage-stabilized power supply, an enabling unit, a negative feedback comparison amplifier unit, a driving tube module unit and a sampling unit;

[0063] The voltage-stabilized power supply is connected to the load unit to supply power to the load unit;

[0064] The negative feedback comparison amplification unit comprises a negative feedback amplifier, a positive input terminal of the negative feedback amplifier is grounded, an inverting input terminal of the negative feedback amplifier is connected to an input signal, and an output terminal of the negative feedback amplifier is connected to an inverting input terminal of the negative feedback amplifier; the output terminal of the negative feedback amplifier is connected to a control terminal of the driving tube module unit;

[0065] The enabling unit is connected to the load unit and the inverting input terminal of the negative feedback amplifier respectively;

[0066] The load unit is connected to the input end of the driving tube module unit, and the driving tube module unit is connected to the inverting input end of the negative feedback amplifier through the sampling unit.

[0067] like Figure 3 As shown, the embodiment of the present application is Figure 2 Based on the above, a specific constant current control circuit is given, including: a voltage-stabilized power supply, an enabling unit, a negative feedback comparison amplifier unit, a driving tube module unit and a sampling unit;

[0068] The voltage-stabilized power supply is connected to the load unit to supply power to the load unit. To ensure the normal operation of the load unit, the embodiment of the present application further includes a load protection unit. The load protection unit is connected to the load unit to protect the load unit.

[0069] Among them, the load protection unit includes a short circuit protection unit and a reverse connection protection unit; the short circuit protection unit is connected to the enabling unit; the short circuit protection unit includes a second switch; the second switch is connected in parallel at both ends of the load unit.

[0070] The reverse connection protection unit includes a fourth diode; the fourth diode is connected in parallel at both ends of the load unit.

[0071] Preferably, the load protection unit further includes a delayed start unit;

[0072] The delayed start unit includes a second capacitor;

[0073] The second capacitor is connected in parallel across the load unit.

[0074] The negative feedback comparison amplification unit comprises a negative feedback amplifier, a positive input terminal of the negative feedback amplifier is grounded, an inverting input terminal of the negative feedback amplifier is connected to an input signal, and an output terminal of the negative feedback amplifier is connected to an inverting input terminal of the negative feedback amplifier; the output terminal of the negative feedback amplifier is connected to a control terminal of the driving tube module unit;

[0075] Specifically, it also includes: a first follower amplifier and a first amplifier; the input signal is connected to the inverting input terminal of the negative feedback amplifier through the first follower amplifier and the first amplifier in sequence.

[0076] The enabling unit is connected to the load unit and the inverting input terminal of the negative feedback amplifier respectively; wherein the enabling unit includes an enabling control unit and an enabling indicating unit;

[0077] The enabling control unit comprises a first switch; one end of the first switch is connected to an enabling signal, and the other end of the first switch is connected to an inverting input end of the negative feedback amplifier through a first diode; when the first switch is in a first state, the first diode is turned on, and when the first switch is in a second state, the first diode is not turned on;

[0078] The enable indication unit includes a second diode, which is a light emitting diode; the other end of the first switch is also grounded through the second diode; when the first switch is in a first state, the second diode is turned on, and when the first switch is in a second state, the second diode is not turned on.

[0079] The load unit is connected to the input end of the driving tube module unit, and the driving tube module unit is connected to the inverting input end of the negative feedback amplifier through the sampling unit.

[0080] The driving pipe module unit is any one of the following:

[0081] MOS tubes, triodes, IGBTs and Darlington tubes.

[0082] As an optional implementation of the embodiment of the present application, in order to limit the current in the circuit, the present application also includes a current limiting protection circuit unit;

[0083] The current limiting protection circuit unit includes a comparison amplifier;

[0084] The first input terminal of the comparison amplifier is connected to the sampling unit; the second input terminal of the comparison amplifier is connected to the current limiting signal; and the output terminal of the comparison amplifier is connected to the inverting input terminal of the negative feedback amplifier.

[0085] Specifically, the current limiting signal is connected to the second input terminal of the comparison amplifier through a second follower amplifier.

[0086] The sampling unit is connected to the first input terminal of the comparison amplifier through a sampling amplifier unit and a third follower amplifier in sequence.

[0087] It can be understood that, since the sampling voltage of the sampling unit is relatively small, a sampling amplification unit is further included; the sampling amplification unit is connected to the sampling unit and is used to amplify the sampling voltage of the sampling unit.

[0088] In one embodiment, the input end of the driving tube module unit is connected to the inverting input end of the negative feedback amplifier through the sampling unit;

[0089] In another embodiment, the output end of the driving tube module unit is connected to the inverting input end of the negative feedback amplifier through the sampling unit.

[0090] As a preferred implementation of this application, Figure 4 As shown, a specific constant current control circuit schematic is given.

[0091] The input signal DAC1 is connected to the non-inverting input terminal of the first follower amplifier U1, the inverting input terminal of the first follower amplifier U1 is connected to its output terminal, the output terminal of the first follower amplifier U1 is connected to the inverting input terminal of the first amplifier U2 through the first resistor R1, the non-inverting input terminal of the first amplifier is grounded, and the inverting input terminal of the first amplifier is also connected to its output terminal through a capacitor. In addition, in order to facilitate the adjustment of the amplification factor of the first amplifier U2, a variable resistor is connected in parallel at both ends of the capacitor. When the resistance value of the variable resistor changes, the amplification factor of the first amplifier U2 changes. The output end of the first amplifier U2 is connected to the inverting input end of the negative feedback amplifier U3 through the third resistor R3 and the fourth resistor R4, the positive input end of the negative feedback amplifier U3 is grounded, the inverting input end of the negative feedback amplifier U3 is also connected to its output end through the third capacitor C3, the gate of the negative feedback amplifier U3 is connected to the gate of the driving tube Q1 (MOS tube) through the fifth resistor, the voltage regulator power supply (i.e., the 5V power supply in the figure) is connected to one end of the load unit LD, the other end of the load unit LD is connected to the drain of the driving tube Q1, the source of the driving tube Q1 is grounded through the sixth resistor R6 (i.e., the sampling resistor or sampling unit), in addition, the source of the driving tube Q1 is also connected to the positive input end of the sampling amplifier unit U4 through the eighth resistor R8, and the inverting input end of the sampling amplifier unit is grounded through the ninth resistor R9. In order to facilitate the variable amplification factor of the sampling amplifier unit U4, the amplifier unit U4 is provided with a variable resistor, and the amplification factor of the sampling amplifier unit U4 is adjusted by changing the resistance value of the variable resistor. The output end of the sampling amplifier unit U4 is connected to the inverting input end of the negative feedback amplifier U3 through the twelfth resistor R12. Preferably, the twelfth resistor R12 is a variable resistor. In order to facilitate monitoring of the current or voltage fed back by the sampling unit, a monitoring point I_Monitor is provided, which is connected to the output end of the sampling amplifier unit U4 through the eleventh resistor R11.

[0092] Among them, the enable signal includes two parts of +12V and -12V, the first switch J1 is a single-pole double-throw switch, connected to +12V and -12V respectively, the first switch J1 is connected to one end of the seventh resistor R7, and the other end of the seventh resistor R7 is connected to the connection point of the third resistor R3 and the fourth resistor R4 through the positive connection of the first diode D1; in addition, the other end of the seventh resistor R7 is grounded through the positive connection of the second diode D2, and the second diode D2 is a light emitting diode.

[0093] A reverse-connected fourth diode D4 is connected in parallel at both ends of the load unit LD for reverse connection prevention. A second capacitor C2 is also connected in parallel at both ends of the load unit LD for delayed start-up. In addition, for short-circuit protection, a second switch J2 is also connected in parallel at both ends of the load unit LD. The first switch J1 and the second switch J2 can be relays.

[0094] The current limiting protection circuit unit mainly consists of the output end of the sampling amplifier unit U4 connected to the positive input end of the third follower amplifier U5, the inverting input end of the third follower amplifier U5 connected to its output end, and the output end of the third follower amplifier U5 connected to the positive input end of the comparison amplifier U7 through the thirteenth resistor R13.

[0095] The current limiting signal DAC2 is connected to the non-inverting input terminal of the second follower amplifier U6, and the inverting input terminal of the second follower amplifier U6 is connected to its output terminal. The output terminal of the second follower amplifier U6 is connected to the inverting input terminal of the comparison amplifier U7 through the fourteenth resistor R14. In order to monitor whether the current limiting signal is accurate, a monitoring point LIM_Monitor is set, which is connected to the output terminal of the second follower amplifier U6 through the fifteenth resistor R15.

[0096] The output end of the comparison amplifier U7 is connected to the inverting input end thereof through the fourth capacitor C4. The output end of the comparison amplifier U7 is connected to the connection point of the third resistor R3 and the fourth resistor R4 through the positive fifth diode D5.

[0097] In order to more clearly illustrate the embodiments of the present application, Figure 4 The constant current control circuit shown is taken as an example for specific description, wherein the load unit LD is a semiconductor laser.

[0098] Assume that the voltage of the input signal DAC1 is V1 after being followed by the first follower amplifier U1 (the first follower amplifier U1 as a follower plays an isolating role, that is, the voltage at the back end does not affect the voltage at the front end, and it does not play an amplifying role), and after being amplified by the first amplifier U2, it becomes V2 = A1*V1 (A1 is the amplification factor of the first amplifier U2, and A1 is determined by the adjustable resistor on the first amplifier U2). Assume that the current passing through the semiconductor laser LD is I, then the current flowing through the sixth resistor R6 (i.e., the sampling unit) is also I, that is, the sampling voltage is R6*I, and after being amplified by the sampling amplifier unit U4, it becomes A2*(R6*I), where A2 is the amplification factor after passing through the sampling amplifier unit U4. According to the virtual short principle, the voltages of the in-phase input terminal and the inverting input terminal of the negative feedback amplifier U3 are equal, that is, Vin+ = Vin- = 0, then the current flowing through the third resistor R3 and the fourth resistor R4 is equal to the current flowing through the twelfth resistor R12, and the direction is opposite, that is,

[0099]

[0100] It can be concluded that:

[0101] In this way, after the parameters R3, R4, R12, R6, A1, and A2 are set, the current I flowing through the semiconductor laser is only related to V1, that is, only related to the input signal DAC1.

[0102] I_Monitor and LIM_Monitor are the current detection point of the set current limit value and the voltage monitoring point of the actual voltage flowing through LD respectively.

[0103] Among them, the constant current control uses the power device field effect tube MOS tube Q1 as the driving tube module unit, and realizes the current control of the load by controlling the gate voltage of the MOS tube Q1. The sampling resistor is connected to the source of the MOS tube Q1. The sampling signal (feedback signal) is subtracted from the set value through the sampling amplifier unit U4 to generate an error signal. The gate voltage of the MOS tube Q1 is adjusted through the integration circuit to achieve the purpose of setting the current as a constant current output.

[0104] In order to keep the input current constant, a voltage-controlled constant current source circuit is designed, with an N-type MOSFET tube (such as IRF3205) as the driving tube and a load in series with it. The sampling resistor R6 is connected to the source of the MOSFET tube.

[0105] The sampling signal is amplified and fed back to the inverting input terminal of U3 for comparison with the set value, generating an error signal to adjust the gate voltage of Q1, so that the voltage VS can control the current IS approximately linearly, and the output current range is 0~30A.

[0106] The field effect tube IRF3205 is used in this case. It has a maximum output current of 110A, VDSS=55V, on-resistance RDS(on)=8.0mΩ, can switch quickly, and can work at 175℃. The high current circuit part is powered by a 5V switching power supply, which can minimize the heat generated by the driver tube. At the same time, the circuit design has heat dissipation treatment for the IRF3205 fan to ensure the safe use of the driver tube.

[0107] After two-stage amplification circuits (the first stage amplification is the first amplifier U2, which mainly amplifies the voltage of the input signal DAC1, and the second stage amplification is the negative feedback amplifier U3, which amplifies the difference between the set current voltage and the actual sampled voltage. Generally, the two-stage method is more flexible), the power device MOS tube Q1 is used as the driving tube. By controlling the gate voltage of the MOS tube Q1, the drain current can be controlled to achieve the effect of voltage-to-current control and realize output current control.

[0108] like Figure 5 As described above, the control of the enabling unit is as follows:

[0109] When the single-pole double-throw switch J1 (i.e., the first switch) is connected to +12V, the first diode D1 and the second diode D2 are both turned on. The voltage of the node PORTA (the right end of the third resistor R3) is clamped to 0. At this time, the gate voltage of the MOS transistor Q1 is lower than the threshold voltage for turning on, and the MOS transistor Q1 operates in the pinch-off region. There is no drain current in the MOS transistor Q1, and no current flows into the LD. This can avoid the fluctuating current or voltage during startup. When the single-pole double-throw switch J1 is connected to -12V, D1 and D2 are not turned on, and the enabling unit does not affect the main circuit.

[0110] Short-circuit protection unit

[0111] If the LD is exposed to the air when not in use, it is vulnerable to lightning or electrostatic damage. Therefore, when not in use, a second switch J2 with a very small contact resistance (a normally closed relay is used in the design) is connected in parallel with the LD to achieve short-circuit protection, as Figure 4 shown.

[0112] When the LD is not working, close S to short-circuit the P and N poles of the LD, which plays a role in protecting the LD; before the LD starts to work, the second switch J2 must be disconnected first so that the current can flow through the LD.

[0113] Delayed soft start

[0114] To prevent damage to the LD caused by instantaneous fluctuations in current or voltage, when in use, the current needs to be slowly applied to both ends of the LD. At the same time, to prevent voltage mutation at the moment of startup, a second capacitor C2 is connected in parallel across the LD. To prevent the reverse connection of the power supply voltage polarity, a fourth diode D4 is connected in reverse across the LD.

[0115] Current-limiting design

[0116] The sampled voltage is amplified by U4 to Va, then isolated by the third follower amplifier, and then compared with the current-limiting signal DAC2. When Va > DAC2, the fifth diode D5 conducts, forming a negative feedback loop, which reduces the current I flowing through the load LD, thereby reducing Va until Va = DAC2. It can be seen that the maximum current flowing through the load LD is a fixed current value related to DAC2. As long as the value of DAC2 (i.e., the current-limiting value) is set, the maximum output current can be obtained, thus protecting the load from being damaged due to overcurrent. When Va < DAC2, the fifth diode D5 does not conduct, and at this time, the circuit does not affect the main circuit.

[0117] The sampling circuit has two working modes:

[0118] 1) Low-end sampling:

[0119] The sampling resistor is connected in series to the source of the driver tube. The advantage of this connection method is that the common-mode signal is small. The disadvantage is that if the drain of the driver tube is short-circuited to the ground, the sampling amplifier unit cannot detect the overcurrent signal in time and may cause load damage.

[0120] 2) High-end sampling:

[0121] The sampling resistor is connected in series at the drain end of the driver tube. The advantage of this connection method is that if the drain is short-circuited to the ground, the sampling amplifier circuit can detect overcurrent and take protective measures (the sampling resistor and the load are on the same side of the driver tube). The disadvantage is that the common-mode signal at both ends of the sampling resistor is large, and the common-mode rejection ratio of the sampling amplifier unit is required to be high.

[0122] The specific constant current control circuit provided in the embodiment of the present application has the following advantages:

[0123] 1. Small current drift over a long period of time and high stability.

[0124] 2. It has multiple protections.

[0125] 3. The maximum current limit can be input and set, and the current limit is self-adjustable and self-protective.

[0126] 4. The actual current can be input and set.

[0127] Based on the same inventive concept, the present application also provides a control system, including:

[0128] The constant current control circuit provided by the above embodiment;

[0129] A load unit connected to the constant current control circuit.

[0130] The control system provided by the embodiment of the present application includes the constant current control circuit provided by the above embodiment, and a load unit connected to the constant current control circuit. The constant current control circuit includes a voltage-stabilized power supply, an enabling unit, a negative feedback comparison amplifier unit, a drive tube module unit and a sampling unit; the voltage-stabilized power supply supplies power to the load unit; when the drive tube module unit is turned on, the load unit is energized, and the sampling unit can obtain the current flowing through the load and then feed it back to the negative feedback comparison amplifier unit, and the negative feedback comparison amplifier unit controls whether the drive tube module unit is turned on. The enabling unit controls whether the negative feedback comparison amplifier unit can control the drive module unit. According to the virtual short, the voltage fed back by the sampling unit is the same as the voltage of the input signal; therefore, when the values ​​of other components are determined, the current that finally flows through the load is only related to the voltage of the input signal. In this way, as long as the voltage of the input signal is ensured to be unchanged, the current flowing through the load unit can be guaranteed to be unchanged.

[0131] Based on the same inventive concept, the present application also provides an electrical device, including the control system provided in the above embodiment.

[0132] The electrical equipment provided in the embodiment of the present application, the control system includes a constant current control circuit and a load unit, the constant current control circuit includes a voltage-stabilized power supply, an enabling unit, a negative feedback comparison amplifier unit, a driving tube module unit and a sampling unit; the voltage-stabilized power supply supplies power to the load unit; when the driving tube module unit is turned on, the load unit is energized, and the sampling unit can obtain the current flowing through the load and then feed it back to the negative feedback comparison amplifier unit, and the negative feedback comparison amplifier unit controls whether the driving tube module unit is turned on. The enabling unit controls whether the negative feedback comparison amplifier unit can control the driving module unit. According to the virtual short, the voltage fed back by the sampling unit is the same as the voltage of the input signal; therefore, when the values ​​of other components are determined, the current that ultimately flows through the load is only related to the voltage of the input signal. In this way, as long as the voltage of the input signal is ensured to remain unchanged, the current flowing through the load unit can be guaranteed to remain unchanged.

[0133] It should be noted that, in the description of this application, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. In addition, in the description of this application, unless otherwise specified, the meaning of "plurality" refers to at least two.

[0134] It can be understood that the same or similar parts of the above embodiments can be referenced to each other, and the contents not described in detail in some embodiments can refer to the same or similar contents in other embodiments.

Claims

1. A constant current control circuit, characterized in that: include: A voltage-stabilized power supply, an enabling unit, a negative feedback comparison amplifier unit, a driving tube module unit and a sampling unit; The voltage-stabilized power supply is connected to the load unit to supply power to the load unit; The negative feedback comparison amplification unit comprises a negative feedback amplifier, a positive input terminal of the negative feedback amplifier is grounded, an inverting input terminal of the negative feedback amplifier is connected to an input signal, and an output terminal of the negative feedback amplifier is connected to an inverting input terminal of the negative feedback amplifier; the output terminal of the negative feedback amplifier is connected to a control terminal of the driving tube module unit; The enabling unit is connected to the load unit and the inverting input terminal of the negative feedback amplifier respectively; The load unit is connected to the input end of the driving tube module unit, and the driving tube module unit is connected to the inverting input end of the negative feedback amplifier through the sampling unit.

2. The constant current control circuit according to claim 1, characterized in that: The enabling unit includes an enabling control unit; The enabling control unit includes a first switch; One end of the first switch is connected to an enable signal, and the other end of the first switch is connected to the inverting input end of the negative feedback amplifier through a first diode; When the first switch is in a first state, the first diode is conductive, and when the first switch is in a second state, the first diode is non-conductive.

3. The constant current control circuit according to claim 2, characterized in that: The enabling unit includes an enabling indicating unit; The enable indication unit includes a second diode, and the second diode is a light emitting diode; The other end of the first switch is also grounded through the second diode; When the first switch is in a first state, the second diode is conductive, and when the first switch is in a second state, the second diode is non-conductive.

4. The constant current control circuit according to claim 1, characterized in that: Also includes a load protection unit; The load protection unit is connected to the load unit and is used to protect the load unit.

5. The constant current control circuit according to claim 4, characterized in that: The load protection unit includes a short circuit protection unit and / or a reverse connection protection unit; The short circuit protection unit is connected to the enabling unit; The short circuit protection unit includes a second switch; The second switch is connected in parallel at both ends of the load unit; The reverse connection protection unit includes a fourth diode; The fourth diode is connected in parallel across the load unit.

6. The constant current control circuit according to claim 4, characterized in that: The load protection unit also includes a delayed start unit; The delayed start unit includes a second capacitor; The second capacitor is connected in parallel across the load unit.

7. The constant current control circuit according to claim 1, characterized in that: It also includes: a current limiting protection circuit unit; The current limiting protection circuit unit includes a comparison amplifier; The first input terminal of the comparison amplifier is connected to the sampling unit; the second input terminal of the comparison amplifier is connected to the current limiting signal; and the output terminal of the comparison amplifier is connected to the inverting input terminal of the negative feedback amplifier.

8. The constant current control circuit according to claim 7, characterized in that: The current limiting signal is connected to the second input terminal of the comparison amplifier through a second follower amplifier.

9. The constant current control circuit according to claim 7, characterized in that: The sampling unit is connected to the first input terminal of the comparison amplifier through a third follower amplifier.

10. The constant current control circuit according to claim 1, characterized in that: Also includes: Sampling and amplification unit; The sampling and amplifying unit is connected to the sampling unit and is used to amplify the sampling voltage of the sampling unit.

11. The constant current control circuit according to claim 1, characterized in that: The input end of the driving tube module unit is connected to the inverting input end of the negative feedback amplifier through the sampling unit; Alternatively, the output end of the driving tube module unit is connected to the inverting input end of the negative feedback amplifier through the sampling unit.

12. The constant current control circuit according to claim 1, characterized in that: Also includes: First follower amplifier; The first follower amplifier is arranged between the input signal and the inverting input terminal of the negative feedback amplifier.

13. The constant current control circuit according to claim 1, characterized in that: Also includes: First amplifier; The first amplifier is arranged between the input signal and an inverting input terminal of the negative feedback amplifier.

14. The constant current control circuit according to claim 1, characterized in that: The driving pipe module unit is any one of the following: MOS tubes, triodes, IGBTs and Darlington tubes.

15. A control system, characterized in that: include: The constant current control circuit according to any one of claims 1 to 14; A load unit connected to the constant current control circuit.

16. An electrical device, characterized in that: Includes the control system described in claim 15.

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