Current sampling integral constant power protection circuit

Abstract

The application relates to a current sampling integral constant power protection circuit, mainly aiming at application occasions with large instantaneous peak current such as motor type products, and comprising the following modules: a current transformer module for realizing current sampling; a current integral module for performing integral operation on the sampling current according to time; a constant power control module for controlling system output constant power; and a hysteresis output module for outputting a control signal. Compared with the prior art, the application has the beneficial effects that: the system can maintain constant power output, in the occasion with large instantaneous working current, the current can be integrated according to time, and the protection can be triggered and the output can be turned off when the upper threshold value is reached, so that the system reliability is improved and the control cost is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of power supply and motor control technology, in particular to a current sampling integral constant power protection circuit. BACKGROUND

[0002] The motor in the circuit is represented by the letter M (old standard uses D), and its main function is to generate driving torque as the power source of electric appliances or various machines. The generator in the circuit is represented by the letter G, and its main function is to convert mechanical energy into electrical energy.

[0003] In the prior art, in the application of motor products, the output instantaneous peak current is large, generally 5-10 times the rated current, in order to meet the use in a short time without triggering protection, the overcurrent protection point needs to be set high, and the power device needs to be selected with large specifications, which will cause the system design to be excessively redundant and cost high. SUMMARY

[0004] In view of the deficiencies in the prior art, the purpose of the present application is to provide a current sampling integral constant power protection circuit which can output constant power and integrate when the instantaneous peak current is large, so as to solve the problems in the background art.

[0005] The above invention purpose of the present application is realized by the following technical scheme:

[0006] A current sampling integral constant power protection circuit, comprising a current transformer module, a current integral module, a constant power control module and a hysteresis output module.

[0007] The current transformer module is used to realize current sampling.

[0008] The current integral module is used to integrate the sampled current according to time.

[0009] The constant power control module is used to control the system to output constant power.

[0010] The hysteresis output module is used to output a control signal.

[0011] In a preferred example, the current transformer module can be further configured to include a current transformer T2, diodes D1 and D2, resistors R1, R2, R3 and R4, and a capacitor C1.

[0012] The capacitor C1, the current transformer T2, the diode D1 and the resistor R2 are connected in the same loop, the resistor R1 is connected in parallel in the loop, the resistor R3 is connected in parallel in the loop after being connected with the resistor R4 in series, and the connection end of the capacitor C1 and the resistor R2 is connected with the current integration module through the diode D2.

[0013] In a preferred example, the current integration module comprises an operational amplifier U1, a capacitor C2 and a resistor R5, the operational amplifier U1 and the capacitor C2 are connected in the same loop, one end of the resistor R5 is connected with the diode D2, and the other end is connected with the output end of the operational amplifier U1.

[0014] In a preferred example, the constant power control module comprises an operational amplifier U3, a resistor R8, a capacitor C4, a diode D4, a resistor R7, a capacitor C3 and a resistor R6.

[0015] The connection end of the R5 and the diode D2 is connected with the resistor R6, the capacitor C3 and the resistor R6 are connected in the same loop, the resistor R8, the capacitor C4 and the operational amplifier U3 are connected in the same loop, the resistor R7 is connected between the loop of the capacitor C3 and the capacitor C4, and the operational amplifier U3 is connected with the hysteresis output module through the diode D4.

[0016] In a preferred example, the hysteresis output module comprises an operational amplifier U2, a diode D3, a diode D5, a triode Q2, a capacitor C5, a resistor R9, a resistor R10 and a resistor R11.

[0017] The operational amplifier U2 and the resistor R11 are connected in the same loop, one end of the diode D3 is connected with the operational amplifier U1, and the other end is connected with the negative electrode of the operational amplifier U2, the resistor R9, the resistor R10 and the diode D5 are connected in the same loop, the operational amplifier U2 is connected with the diode D5 and the resistor R9 respectively, and the triode Q2 and the capacitor C5 are connected in the same loop and then connected with the resistor R9 and the resistor R10 respectively.

[0018] In summary, the present application has at least one of the following beneficial technical effects:

[0019] The main circuit (primary side) current is converted to the secondary side by using the current transformer T2, and then converted into a voltage signal, which is respectively given to the operational amplifier U1 and U3. The operational amplifier U3 constitutes a constant power control module. When the load end current increases, the U3 in-phase terminal detects that the voltage rises, the output signal of the adjusting operational amplifier decreases, the FB signal decreases, and the output voltage decreases, so as to control the input power to be constant. When the load end current exceeds Vref1 after conversion, the inverting integral circuit module constituted by U1 starts to work. When the integral upper limit is reached, the output of U1 is a negative voltage, D3 is turned on, the U2 inverting terminal is pulled to a low level, at this time, Vref2 is greater than the inverting terminal voltage, and the output of U2 is a high level. Due to the increase of the hysteresis module, Q2 will not be turned on immediately. When the voltage of C5 rises to the Q2 turn-on voltage, Q2 starts to be turned on, FB is pulled to a low level, and the output is turned off, so as to achieve the purpose of transient overload protection. The circuit can maintain the system to keep constant power output. When a large peak current appears in the system, the sampled current is integrated to control the system to trigger protection and turn off the output when the threshold is reached. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 It is the overall circuit diagram of the application.

[0021] Figure 2 It is Figure 1 It is the partial enlarged schematic view of the A part in the middle.

[0022] Reference signs

[0023] 1, current transformer module; 2, current integral module; 3, constant power control module; 4, hysteresis output module. DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments of the application will be clearly and completely described below with reference to the drawings in the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, not all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the application.

[0025] In the description of the application, it should be noted that the terms "upper", "lower", "inner", "outer", "top / bottom end" and the like indicate the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the application. In addition, the terms "first", "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0026] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "provided with", "sleeved / connected", "connected" and the like should be understood in a broad sense, for example, "connected" can be fixedly connected, or detachably connected, or integrally connected; can be mechanically connected, or electrically connected; can be directly connected, or indirectly connected through an intermediate medium, or can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0027] Embodiment one:

[0028] Referring to Figures 1-2 The application discloses a current sampling integral constant power protection circuit, which comprises a current transformer module 1, a current integral module 2, a constant power control module 3 and a hysteresis output module 4.

[0029] The current transformer module 1 is used for realizing current sampling.

[0030] The current integral module 2 is used for performing integral operation on the sampled current according to time.

[0031] The constant power control module 3 is used for controlling the system to output constant power.

[0032] The hysteresis output module 4 is used for outputting a control signal.

[0033] The current transformer module 1 comprises a current transformer T2, diodes D1 and D2, resistors R1, R2, R3 and R4 and a capacitor C1. The capacitor C1, the current transformer T2, the diode D1 and the resistor R2 are connected in the same loop, the resistor R1 is connected in parallel in the loop, the resistor R3 is connected in parallel with the resistor R4 in the loop, and the connection end of the capacitor C1 and the resistor R2 is connected with the current integral module 2 through the diode D2.

[0034] The current integral module 2 comprises an operational amplifier U1, a capacitor C2 and a resistor R5. The operational amplifier U1 and the capacitor C2 are connected in the same loop, one end of the resistor R5 is connected with the diode D2, and the other end is connected with the output end of the operational amplifier U1.

[0035] The constant power control module 3 comprises an operational amplifier U3, a resistor R8, a capacitor C4, a diode D4, a resistor R7, a capacitor C3 and a resistor R6. The connection end of the resistor R5 and the diode D2 is connected with the resistor R6, the capacitor C3 is connected with the resistor R6 in the same loop, the resistor R8, the capacitor C4 and the operational amplifier U3 are connected in the same loop, the resistor R7 is connected between the loop of the capacitor C3 and the capacitor C4, and the operational amplifier U3 is connected with the hysteresis output module 4 through the diode D4.

[0036] The hysteresis output module 4 comprises an operational amplifier U2, a diode D3, a diode D5, a transistor Q2, a capacitor C5, a resistor R9, a resistor R10 and a resistor R11. The operational amplifier U2 is connected in the same loop with the resistor R11, one end of the diode D3 is connected with the operational amplifier U1, the other end is connected with the negative pole of the operational amplifier U2, the resistor R9, the resistor R10 and the diode D5 are connected in the same loop, the operational amplifier U2 is connected with the diode D5 and the resistor R9 respectively, and the transistor Q2 is connected in the same loop with the capacitor C5, and then connected with the resistor R9 and the resistor R10 respectively.

[0037] The implementation principle of the embodiment is that: the current transformer T2 is used to convert the main circuit (primary side) current to the secondary side through the turns ratio, and then convert it into a voltage signal, which is respectively given to the operational amplifier U1 and U3. The operational amplifier U3 constitutes a constant power control module 3, when the load end current increases, the U3 in-phase end detects that the voltage rises, adjusts the operational amplifier output signal to decrease, so that the FB signal decreases, and the output voltage decreases, so as to control the input power constant; when the load end current is converted and exceeds Vref1, the opposite phase integral circuit module constituted by U1 starts to work, when the integral upper limit is reached, the U1 output is negative voltage, D3 is turned on, and the U2 opposite phase end is pulled to low level, at this time, Vref2 is greater than the opposite phase end voltage, U2 output is high level, because the hysteresis module is increased, Q2 will not be turned on immediately, when the C5 voltage rises to the Q2 turn-on voltage, Q2 starts to conduct, and FB is pulled to low potential, and the output is turned off, so as to achieve the purpose of transient overload protection. The circuit can maintain the system to keep constant power output, when the system appears a larger peak current, the sampled current is integrated to control the system to trigger protection and turn off the output when reaching the threshold time.

[0038] The embodiments of the specific embodiment are the preferred embodiments of the application, which do not limit the protection scope of the application, so that: any equivalent changes made according to the structure, shape, principle of the application should be covered in the protection scope of the application.

Claims

1. A current sampling integral constant power protection circuit, characterized in that: It includes a current transformer module (1), a current integration module (2), a constant power control module (3), and a hysteresis output module (4); The current transformer module (1) is used to implement current sampling; The current integration module (2) is used to integrate the sampled current over time. The constant power control module (3) is used to control the system to output constant power; The hysteresis output module (4) is used to output control signals; The current integration module (2) includes an operational amplifier U1, a capacitor C2 and a resistor R5. The inverting input terminal of the operational amplifier U1 is connected to one end of the capacitor C2, and the other end of the capacitor C2 is connected to the output terminal of the operational amplifier U1. One end of the resistor R5 is connected to the output terminal of the current transformer module (1), and the other end is connected to the inverting input terminal of the operational amplifier U1. The constant power control module (3) includes an operational amplifier U3, a resistor R8, a capacitor C4, a diode D4, a resistor R7, a capacitor C3, and a resistor R6; The connection point of resistor R5 to the output terminal of the current transformer module (1) is connected to one end of resistor R6, and the other end of resistor R6 is grounded. Capacitor C3 is connected in parallel with resistor R6. Resistor R8 is connected in series with capacitor C4 and then in parallel between the inverting input terminal and the output terminal of operational amplifier U3. Resistor R7 is connected in series between capacitor C3 and capacitor C4. Operational amplifier U3 is connected to the hysteresis output module (4) through diode D4. The non-inverting input terminal of operational amplifier U3 is connected to Vref3. The hysteresis output module (4) includes an operational amplifier U2, a diode D3, a diode D5, a transistor Q2, a capacitor C5, a resistor R9, a resistor R10, and a resistor R11; The inverting input terminal of the operational amplifier U2 is connected to one end of the resistor R11. One end of the diode D3 is connected to the output terminal of the operational amplifier U1, and the other end is connected to the inverting input terminal of the operational amplifier U2. The output terminal of the operational amplifier U2 is connected to one end of the resistor R9 and the anode of the diode D5. The cathode of the diode D5 is connected to one end of the resistor R10. The other ends of the resistors R9 and R10 are connected to the base of the transistor Q2. One end of the capacitor C5 is connected to the base of the transistor Q2, and the other end is grounded. The main circuit current is converted to the secondary side using a current transformer T2 through turns ratio calculation, and then converted into a voltage signal, which is supplied to operational amplifiers U1 and U3 respectively. Operational amplifier U3 constitutes a constant power control module 3. When the load current increases, the inverting input terminal of operational amplifier U3 detects the voltage increase and adjusts the output signal of the operational amplifier to decrease, thereby reducing the FB signal and lowering the output voltage, thus controlling the input power to be constant. When the load current exceeds Vref1 after conversion, the inverting integrator circuit module composed of operational amplifier U1 starts to work. When the integration upper limit is reached, operational amplifier U1... When the output is negative, diode D3 conducts, pulling the inverting input of operational amplifier U2 low. At this time, Vref2 is greater than the voltage at the inverting input, and operational amplifier U2 outputs a high level. Due to the added hysteresis module, transistor Q2 will not conduct immediately. When the voltage of capacitor C5 rises to the conduction voltage of transistor Q2, transistor Q2 starts to conduct, pulling FB low to a low potential and turning off the output, thus achieving transient overload protection. This circuit can maintain the system at a constant power output. When the system experiences a large instantaneous peak current, the sampled current is integrated to control the system to trigger protection and shut down the output when the threshold is reached.

2. The current sampling integral constant power protection circuit according to claim 1, characterized in that: The current transformer module (1) includes a current transformer T2, diode D1, diode D2, resistor R1, resistor R2, resistor R3, resistor R4 and capacitor C1; The capacitor C1, the current transformer T2, the diode D1 and the resistor R2 are connected in series. The resistor R1 is connected in parallel with the secondary side of the current transformer T2. The resistor R3 and the resistor R4 are connected in series, with one end connected to the cathode of the diode D1 and the other end grounded. The connection end of the capacitor C1 and the resistor R2 is connected to the current integration module (2) through the diode D2.

Images