CN218848215U - VGA-based constant power load device - Google Patents
VGA-based constant power load device Download PDFInfo
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- CN218848215U CN218848215U CN202223416135.5U CN202223416135U CN218848215U CN 218848215 U CN218848215 U CN 218848215U CN 202223416135 U CN202223416135 U CN 202223416135U CN 218848215 U CN218848215 U CN 218848215U
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Abstract
The utility model provides a constant power load device based on VGA in the technical field of instruments and meters, which comprises a power control circuit, a power output protection circuit, a voltage sampling circuit and a current sampling circuit; the input end of the power control circuit is connected with the output end of the voltage sampling circuit and the output end of the current sampling circuit, and the output end of the power control circuit is connected with the input end of the power output protection circuit; and the output end of the power output protection circuit is connected with the input end of the voltage sampling circuit and the input end of the current sampling circuit. The utility model has the advantages that: the precision, response speed and cost of balancing the constant power load are realized.
Description
Technical Field
The utility model relates to an instrument and meter technical field indicates a constant power load device based on VGA very much.
Background
Constant power loads are usually needed to judge the discharge performance of equipment such as an energy storage battery, a direct current stabilized power supply and the like; in servo instrumentation, a constant power load is also required to verify the dynamic characteristics of the drive. The existing constant power load is divided into a digital type and an analog type, the current value and the load voltage value in a sampling power loop are sent to a DSP chip in the digital type to be calculated to obtain the current power, and the power consumption of the load is adjusted by means of control modes such as PID (proportion integration differentiation) and the like to achieve a steady state; the analog type sends the voltage value and the current value of the load into the analog multiplier chip to obtain the current power.
The power output of a digital constant-power load is generally more accurate and has high response speed, a certain amount of control and filtering algorithms are conveniently integrated, but the cost is far higher than that of an analog type; the analog constant-power load has the advantages of simple circuit structure and low cost, but the control precision and the response speed are not high.
Therefore, how to provide a constant power load device based on VGA to realize the precision, response speed and cost of balancing the constant power load becomes a technical problem to be solved urgently.
Disclosure of Invention
The to-be-solved technical problem of the utility model lies in providing a constant power load device based on VGA, realizes precision, response speed and the cost of balanced constant power load.
The utility model discloses a realize like this: a constant power load device based on VGA comprises a power control circuit, a power output protection circuit, a voltage sampling circuit and a current sampling circuit;
the input end of the power control circuit is connected with the output end of the voltage sampling circuit and the output end of the current sampling circuit, and the output end of the power control circuit is connected with the input end of the power output protection circuit; and the output end of the power output protection circuit is connected with the input end of the voltage sampling circuit and the input end of the current sampling circuit.
Further, the power control circuit includes a VGA chip U5, an operational amplifier U2A, an operational amplifier U4B, a resistor R27, a resistor R28, a resistor R29, a resistor R30, a resistor R33, a resistor R34, a resistor R36, a resistor R38, a capacitor C7, a capacitor C8, a capacitor C9, a capacitor C10, a capacitor C12, and a capacitor C13;
a pin 1 of the operational amplifier U2A is connected with a capacitor C8, a capacitor C9 and a power output protection circuit, a pin 2 is connected with a resistor R29 and a capacitor C8, a pin 3 is connected with a resistor R27, and a pin 8 is connected with a capacitor C7; the resistor R27 is connected with a power output protection circuit;
Further, the power output protection circuit includes an optocoupler U1, a DCDC chip U3, an MOS transistor Q1, a triode Q2, a triode Q3, a zener diode D1, a zener diode D3, a capacitor C4, a capacitor C5, a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R6, a resistor R7, a resistor R8, a resistor R10, a resistor R12, a resistor R13, a resistor R14, a resistor R15, a resistor R16, a resistor R21, a resistor R22, a resistor R23, a resistor R24, and a resistor R26;
one end of the capacitor U4 is connected with a pin 1 of the DCDC chip U3, and the other end of the capacitor U4 is connected with a pin 2 of the DCDC chip U3; one end of the capacitor C5 is connected with the pin 4 of the DCDC chip U3, the resistor R26, the resistor R13, the resistor R14 and the input end of the voltage stabilizing diode D3, and the other end of the capacitor C5 is connected with the pin 6 of the DCDC chip U3 and the resistor R6;
a pin 1 of the optocoupler U1 is connected with a resistor R7, a resistor R10 and a drain electrode of the MOS transistor Q1, a pin 2 is connected with the resistor R10 and grounded, a pin 3 is connected with a resistor R8, a resistor R12 and an output end of the voltage stabilizing diode D1, and a pin 4 is connected with a resistor R6; the grid electrode of the MOS tube Q1 is connected with the resistor R3 and the resistor R4, and the source electrode of the MOS tube Q1 is connected with the resistor R4; the resistor R7 is connected with the power control circuit; the output end of the voltage stabilizing diode D3 is connected with the input end of the voltage stabilizing diode D1;
after the resistor R1 and the resistor R2 are connected in parallel, one end of the resistor R is connected with the voltage sampling circuit, and the other end of the resistor R is connected with a pin 2 of the triode Q2 and a pin 2 of the triode Q3; after the resistor R21, the resistor R22, the resistor R23 and the resistor R24 are connected in parallel, one end of the resistor R26, the voltage sampling circuit and the current sampling circuit are connected, and the other end of the resistor R15, the resistor R16 and the current sampling circuit are connected;
a pin 1 of the triode Q2 is connected with a resistor R8 and a resistor R13, and a pin 3 is connected with a resistor R15; and a pin 1 of the triode Q3 is connected with a resistor R12 and a resistor R14, and a pin 3 is connected with a resistor R16.
Further, the voltage sampling circuit includes a relay K1, an operational amplifier U2B, a diode D2, an MOS transistor Q4, a capacitor C1, a capacitor C2, a capacitor C3, a capacitor C6, an adjustable resistor R5, a resistor R9, a resistor R11, a resistor R17, a resistor R18, a resistor R19, a resistor R20, and a resistor R25;
a pin 1 of the relay K1 is connected with an output end of a resistor R18, a capacitor C6 and a diode D2, a pin 3 is connected with a pin 5 of an operational amplifier U2B, the pin 5 is connected with an adjustable resistor R5, a resistor R11 and a capacitor C1, a pin 7 is connected with the resistor R11, the resistor R17 and the capacitor C3, and a pin 8 is connected with an input end of the diode D2 and a drain electrode of an MOS (metal oxide semiconductor) transistor Q4;
one end of the resistor R9 is connected with the capacitor C2 and the power control circuit, and the other end of the resistor R9 is connected with pins 6 and 7 of the operational amplifier U2B; the gate of the MOS transistor Q4 is connected with the resistor R20 and the resistor R25, and the source is connected with the resistor R25;
one end of the resistor R19 is connected with the resistor R17, the capacitor C1, the capacitor C3 and the power output protection circuit, and the other end of the resistor R19 is grounded; the adjustable resistor R5 is connected with the power output protection circuit.
Further, the current sampling circuit includes an operational amplifier U4A, a capacitor C11, a capacitor C14, a capacitor C15, a resistor R31, a resistor R32, a resistor R35, and a resistor R37;
one end of the resistor R32 is connected with the resistor R31 and the pin 3 of the operational amplifier U4A, and the other end of the resistor R is connected with the power output protection circuit; one end of the resistor R35 is connected with the resistor R37, the capacitor C15 and the pin 2 of the operational amplifier U4A, and the other end of the resistor R35 is connected with the power output protection circuit; one end of the capacitor C11 is connected with a pin 8 of the operational amplifier U4A, and the other end of the capacitor C is grounded; one end of the capacitor C14 is connected with a pin 4 of the operational amplifier U4A, and the other end of the capacitor C is grounded; and the pin 1 of the operational amplifier U4A is connected with the resistor R37, the capacitor C15 and the power control circuit.
The utility model has the advantages that:
by arranging the power control circuit, the power output protection circuit, the voltage sampling circuit and the current sampling circuit, the input ends of the voltage sampling circuit and the current sampling circuit are connected with the power output protection circuit, the output end is connected with the power control circuit, the output end of the power control circuit is connected with the input end of the power output protection circuit, the power control circuit adjusts the power of the power output protection circuit based on the voltage value and the current value acquired by the voltage sampling circuit and the current sampling circuit, the power control circuit adopts a VGA chip U5 to replace a traditional analog multiplier chip, the hardware cost of a constant-power load device is effectively reduced, the precision and the response speed of power adjustment are guaranteed, namely, the precision of a constant-power load, the response speed and the cost are balanced.
Drawings
The invention will be further described with reference to the following examples with reference to the accompanying drawings.
Fig. 1 is a schematic circuit block diagram of a constant power load device based on VGA of the present invention.
Fig. 2 is a circuit diagram of the power control circuit of the present invention.
Fig. 3 is a circuit diagram of the power output protection circuit of the present invention.
Fig. 4 is a circuit diagram of the voltage sampling circuit of the present invention.
Fig. 5 is a circuit diagram of the current sampling circuit of the present invention.
Detailed Description
The embodiment of the utility model provides a through providing a constant power load device based on VGA, it is with high costs to have solved the constant power load of digital among the prior art, and the technical problem that the control accuracy and the response speed of the constant power load of analog are low has realized the technological effect of the precision, response speed and the cost of balanced constant power load.
The embodiment of the utility model provides an in technical scheme for solving above-mentioned problem, the general thinking is as follows: the power of the power output protection circuit is adjusted through the power control circuit provided with the VGA chip U5, so that the hardware cost of the constant-power load device is reduced, and the accuracy and the response speed of power adjustment are guaranteed.
For better understanding of the above technical solutions, the following detailed descriptions will be provided in conjunction with the drawings and the detailed description of the embodiments.
Referring to fig. 1 to 5, a preferred embodiment of a constant power load device based on VGA includes a power control circuit, a power output protection circuit, a voltage sampling circuit and a current sampling circuit; the power control circuit is used for constant power control; the power output protection circuit is used for discharging and overcurrent protection; the voltage sampling circuit is used for sampling the load voltage; the current sampling circuit is used for sampling the load current;
the input end of the power control circuit is connected with the output end of the voltage sampling circuit and the output end of the current sampling circuit, and the output end of the power control circuit is connected with the input end of the power output protection circuit; and the output end of the power output protection circuit is connected with the input end of the voltage sampling circuit and the input end of the current sampling circuit.
The power control circuit comprises a VGA chip U5, an operational amplifier U2A, an operational amplifier U4B, a resistor R27, a resistor R28, a resistor R29, a resistor R30, a resistor R33, a resistor R34, a resistor R36, a resistor R38, a capacitor C7, a capacitor C8, a capacitor C9, a capacitor C10, a capacitor C12 and a capacitor C13; the model of the VGA chip U5 is preferably AD8337BCPZ;
the operational amplifier U2A, the resistor R27, the resistor R29, the capacitor C7, the capacitor C8 and the capacitor C9 form an overcurrent protection output circuit, and once the voltage value of the current sampling signal Is exceeds an overcurrent protection SET value IPRT _ SET, a high-level signal Is output to perform protection action; the resistor R36 and the resistor R38 are loop gain resistors and are used for stabilizing a preamplifier in the VGA chip U5; the resistor R33 and the resistor R34 are low-resistance current-limiting resistors, and the capacitor C12 and the capacitor C13 are power supply decoupling capacitors; the network number ThmPad represents a heat dissipation pad of the VGA chip U5, and is not electrically connected with other networks; the operational amplifier U4B, the resistor R28, the resistor R30 and the capacitor C10 form an integrator; the VGA chip U5 outputs the product of the sampled current and voltage (i.e., the present power), and feeds the product together with the power setting signal PWR _ SET into the integrator to generate the power control signal CP _ OUT for stabilizing the load power.
A pin 1 of the operational amplifier U2A is connected with a capacitor C8, a capacitor C9 and a power output protection circuit, a pin 2 is connected with a resistor R29 and a capacitor C8, a pin 3 is connected with a resistor R27, and a pin 8 is connected with a capacitor C7; the resistor R27 is connected with a power output protection circuit;
The power output protection circuit comprises an optocoupler U1, a DCDC chip U3, an MOS tube Q1, a triode Q2, a triode Q3, a voltage-regulator diode D1, a voltage-regulator diode D3, a capacitor C4, a capacitor C5, a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R6, a resistor R7, a resistor R8, a resistor R10, a resistor R12, a resistor R13, a resistor R14, a resistor R15, a resistor R16, a resistor R21, a resistor R22, a resistor R23, a resistor R24 and a resistor R26; the type of the optocoupler U1 is preferably SFH6156;
the resistor R1 and the resistor R2 are current-limiting resistors; the resistor R15 and the resistor R16 are triode emitter current equalizing resistors and are used for balancing the power consumption of the triode Q2 and the power consumption of the triode Q3; the resistor R21, the resistor R22, the resistor R23 and the resistor R24 are current sampling resistors; the triode Q2 and the triode Q3 are power output triodes, and the optocoupler U1, the resistor R6, the resistor R7, the resistor R8, the resistor R10, the resistor R12, the resistor R13 and the resistor R14 are triode isolation driving circuits; the voltage-stabilizing triode D1 and the voltage-stabilizing triode D3 are used for preventing the triode base level from being damaged by overvoltage; the DCDC chip U3, the capacitor C4 and the capacitor C5 are isolated DC/DC power circuits and are used for generating a power supply of the triode drive circuit, and the power supply is represented by network numbers BJTCON + and BJTCON-; the MOS tube Q1, the resistor R3 and the resistor R4 are overcurrent protection circuits, when a control signal CP _ PRT is at a high level, the control end of the optocoupler U1 is pulled down, so that the power output triode is in a turn-off state, and a protection effect is achieved; the resistor R26 is a zero-ohm resistor and is used for short-circuiting the cathode of the bus and the isolated driving power supply BJTCON-, so that the two are connected at a single point.
One end of the capacitor U4 is connected with a pin 1 of the DCDC chip U3, and the other end of the capacitor U4 is connected with a pin 2 of the DCDC chip U3; one end of the capacitor C5 is connected with the pin 4 of the DCDC chip U3, the resistor R26, the resistor R13, the resistor R14 and the input end of the voltage stabilizing diode D3, and the other end of the capacitor C5 is connected with the pin 6 of the DCDC chip U3 and the resistor R6;
a pin 1 of the optocoupler U1 is connected with a resistor R7, a resistor R10 and a drain electrode of the MOS transistor Q1, a pin 2 is connected with the resistor R10 and grounded, a pin 3 is connected with a resistor R8, a resistor R12 and an output end of the voltage stabilizing diode D1, and a pin 4 is connected with a resistor R6; the grid electrode of the MOS tube Q1 is connected with the resistor R3 and the resistor R4, and the source electrode of the MOS tube Q1 is connected with the resistor R4; the resistor R7 is connected with the power control circuit; the output end of the voltage stabilizing diode D3 is connected with the input end of the voltage stabilizing diode D1;
after the resistor R1 and the resistor R2 are connected in parallel, one end of the resistor R is connected with the voltage sampling circuit, and the other end of the resistor R is connected with a pin 2 of the triode Q2 and a pin 2 of the triode Q3; after the resistor R21, the resistor R22, the resistor R23 and the resistor R24 are connected in parallel, one end of the resistor R is connected with the resistor R26, the voltage sampling circuit and the current sampling circuit, and the other end of the resistor R is connected with the resistor R15, the resistor R16 and the current sampling circuit;
a pin 1 of the triode Q2 is connected with a resistor R8 and a resistor R13, and a pin 3 is connected with a resistor R15; and a pin 1 of the triode Q3 is connected with a resistor R12 and a resistor R14, and a pin 3 is connected with a resistor R16.
The voltage sampling circuit comprises a relay K1, an operational amplifier U2B, a diode D2, an MOS tube Q4, a capacitor C1, a capacitor C2, a capacitor C3, a capacitor C6, an adjustable resistor R5, a resistor R9, a resistor R11, a resistor R17, a resistor R18, a resistor R19, a resistor R20 and a resistor R25;
network numbers VBUS + and VBUS-represent the positive and negative poles of the direct current bus, and the resistor R5, the resistor R11 and the resistor R17 are voltage dividing resistors and are used for obtaining voltage applied to a load after voltage division; the capacitor C1 and the capacitor C3 are filter capacitors and are used for stabilizing voltage sampling values; the resistor R19 is a zero ohm resistor and is used for short-circuiting the cathode of the bus and the sampling ground level of the system so as to connect the two at a single point; the relay K1 is used for switching the voltage after the resistance voltage division and can adapt to the bus voltage of two voltage grades; the resistor R18, the resistor R20, the resistor R25, the capacitor C6, the diode D2 and the MOS tube Q4 are peripheral driving circuit devices of the relay K1; the operational amplifier U2B is a voltage sampling buffer, and the resistor R9 and the capacitor C2 are used for further filtering noise of the sampled voltage; the output of the voltage sampling circuit is a network number Vs.
A pin 1 of the relay K1 is connected with an output end of a resistor R18, a capacitor C6 and a diode D2, a pin 3 is connected with a pin 5 of an operational amplifier U2B, the pin 5 is connected with an adjustable resistor R5, a resistor R11 and a capacitor C1, a pin 7 is connected with the resistor R11, the resistor R17 and the capacitor C3, and a pin 8 is connected with an input end of the diode D2 and a drain electrode of an MOS (metal oxide semiconductor) transistor Q4;
one end of the resistor R9 is connected with the capacitor C2 and the power control circuit, and the other end of the resistor R9 is connected with pins 6 and 7 of the operational amplifier U2B; the gate of the MOS transistor Q4 is connected with the resistor R20 and the resistor R25, and the source is connected with the resistor R25;
one end of the resistor R19 is connected with the resistor R17, the capacitor C1, the capacitor C3 and the power output protection circuit, and the other end of the resistor R19 is grounded; the adjustable resistor R5 is connected with the power output protection circuit.
The current sampling circuit comprises an operational amplifier U4A, a capacitor C11, a capacitor C14, a capacitor C15, a resistor R31, a resistor R32, a resistor R35 and a resistor R37;
the operational amplifier U4A, the resistor R31, the resistor R32, the resistor R35 and the resistor R37 form a differential amplifying circuit, and signals at two ends of a current sampling resistor in the power output protection circuit are extracted and amplified; the capacitor C15 is a filter capacitor and is used for stabilizing a sampling signal; the capacitor C11 and the capacitor C14 are power supply decoupling capacitors, and the power supply quality of the operational amplifier is improved; the output network number of the current sampling circuit IS IS _ OUT.
One end of the resistor R32 is connected with the resistor R31 and the pin 3 of the operational amplifier U4A, and the other end of the resistor R is connected with the power output protection circuit; one end of the resistor R35 is connected with the resistor R37, the capacitor C15 and the pin 2 of the operational amplifier U4A, and the other end of the resistor R35 is connected with the power output protection circuit; one end of the capacitor C11 is connected with a pin 8 of the operational amplifier U4A, and the other end of the capacitor C is grounded; one end of the capacitor C14 is connected with a pin 4 of the operational amplifier U4A, and the other end of the capacitor C is grounded; and the pin 1 of the operational amplifier U4A is connected with the resistor R37, the capacitor C15 and the power control circuit.
The utility model discloses the theory of operation:
the constant-power load device is loaded on a direct-current bus VBUS + and VBUS-, and the voltage sampling circuit and the current sampling circuit sample the voltage value and the current value of the direct-current bus in real time and send the sampled voltage value and current value to the power control circuit; the power control circuit calculates the power of the current load based on the input voltage value and the current value, and controls the discharge degree of the power output protection circuit after comparing the power with the preset power, thereby achieving the effect of constant power.
To sum up, the utility model has the advantages that:
by arranging the power control circuit, the power output protection circuit, the voltage sampling circuit and the current sampling circuit, the input ends of the voltage sampling circuit and the current sampling circuit are connected with the power output protection circuit, the output end is connected with the power control circuit, the output end of the power control circuit is connected with the input end of the power output protection circuit, the power control circuit adjusts the power of the power output protection circuit based on the voltage value and the current value acquired by the voltage sampling circuit and the current sampling circuit, the power control circuit adopts a VGA chip U5 to replace a traditional analog multiplier chip, the hardware cost of a constant-power load device is effectively reduced, the precision and the response speed of power adjustment are guaranteed, namely, the precision of a constant-power load, the response speed and the cost are balanced.
Although specific embodiments of the present invention have been described, it will be understood by those skilled in the art that the specific embodiments described are illustrative only and are not limiting upon the scope of the invention, and that equivalent modifications and variations can be made by those skilled in the art without departing from the spirit of the invention, which is to be limited only by the claims appended hereto.
Claims (5)
1. A constant power load device based on VGA is characterized in that: comprises a power control circuit, a power output protection circuit, a voltage sampling circuit and a current sampling circuit;
the input end of the power control circuit is connected with the output end of the voltage sampling circuit and the output end of the current sampling circuit, and the output end of the power control circuit is connected with the input end of the power output protection circuit; and the output end of the power output protection circuit is connected with the input end of the voltage sampling circuit and the input end of the current sampling circuit.
2. A VGA based constant power load apparatus as recited in claim 1, wherein: the power control circuit comprises a VGA chip U5, an operational amplifier U2A, an operational amplifier U4B, a resistor R27, a resistor R28, a resistor R29, a resistor R30, a resistor R33, a resistor R34, a resistor R36, a resistor R38, a capacitor C7, a capacitor C8, a capacitor C9, a capacitor C10, a capacitor C12 and a capacitor C13;
a pin 1 of the operational amplifier U2A is connected with a capacitor C8, a capacitor C9 and a power output protection circuit, a pin 2 is connected with a resistor R29 and a capacitor C8, a pin 3 is connected with a resistor R27, and a pin 8 is connected with a capacitor C7; the resistor R27 is connected with a power output protection circuit;
pin 1 of the VGA chip U5 is connected to the resistor R30, pin 3 is connected to the resistor R34, pin 4 is connected to the resistor R36 and the resistor R38, pin 5 is connected to the resistor R36, pin 6 is connected to the capacitor C13, pin 7 is connected to the resistor R33, and pin 8 is connected to the capacitor C12; the resistor R34 is connected with the current sampling circuit; the resistor R33 is connected with the voltage sampling circuit; and a pin 5 of the operational amplifier U4B is connected with a resistor R28, a pin 6 is connected with a resistor R30 and a capacitor C10, and a pin 7 is connected with a capacitor C10 and a power output protection circuit.
3. A VGA based constant power load apparatus as recited in claim 1, wherein: the power output protection circuit comprises an optocoupler U1, a DCDC chip U3, an MOS tube Q1, a triode Q2, a triode Q3, a voltage-regulator diode D1, a voltage-regulator diode D3, a capacitor C4, a capacitor C5, a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R6, a resistor R7, a resistor R8, a resistor R10, a resistor R12, a resistor R13, a resistor R14, a resistor R15, a resistor R16, a resistor R21, a resistor R22, a resistor R23, a resistor R24 and a resistor R26;
one end of the capacitor U4 is connected with a pin 1 of the DCDC chip U3, and the other end of the capacitor U4 is connected with a pin 2 of the DCDC chip U3; one end of the capacitor C5 is connected with the pin 4 of the DCDC chip U3, the resistor R26, the resistor R13, the resistor R14 and the input end of the voltage stabilizing diode D3, and the other end of the capacitor C5 is connected with the pin 6 of the DCDC chip U3 and the resistor R6;
a pin 1 of the optocoupler U1 is connected with a resistor R7, a resistor R10 and a drain electrode of the MOS transistor Q1, a pin 2 is connected with the resistor R10 and grounded, a pin 3 is connected with a resistor R8, a resistor R12 and an output end of the voltage stabilizing diode D1, and a pin 4 is connected with a resistor R6; the grid electrode of the MOS tube Q1 is connected with the resistor R3 and the resistor R4, and the source electrode of the MOS tube Q1 is connected with the resistor R4; the resistor R7 is connected with the power control circuit; the output end of the voltage stabilizing diode D3 is connected with the input end of the voltage stabilizing diode D1;
after the resistor R1 and the resistor R2 are connected in parallel, one end of the resistor R1 is connected with the voltage sampling circuit, and the other end of the resistor R2 is connected with a pin 2 of the triode Q2 and a pin 2 of the triode Q3; after the resistor R21, the resistor R22, the resistor R23 and the resistor R24 are connected in parallel, one end of the resistor R26, the voltage sampling circuit and the current sampling circuit are connected, and the other end of the resistor R15, the resistor R16 and the current sampling circuit are connected;
a pin 1 of the triode Q2 is connected with a resistor R8 and a resistor R13, and a pin 3 is connected with a resistor R15; and a pin 1 of the triode Q3 is connected with a resistor R12 and a resistor R14, and a pin 3 is connected with a resistor R16.
4. The VGA based constant power load apparatus of claim 1, wherein: the voltage sampling circuit comprises a relay K1, an operational amplifier U2B, a diode D2, an MOS tube Q4, a capacitor C1, a capacitor C2, a capacitor C3, a capacitor C6, an adjustable resistor R5, a resistor R9, a resistor R11, a resistor R17, a resistor R18, a resistor R19, a resistor R20 and a resistor R25;
a pin 1 of the relay K1 is connected with an output end of a resistor R18, a capacitor C6 and a diode D2, a pin 3 is connected with a pin 5 of an operational amplifier U2B, the pin 5 is connected with an adjustable resistor R5, a resistor R11 and a capacitor C1, a pin 7 is connected with the resistor R11, the resistor R17 and the capacitor C3, and a pin 8 is connected with an input end of the diode D2 and a drain electrode of an MOS (metal oxide semiconductor) transistor Q4;
one end of the resistor R9 is connected with the capacitor C2 and the power control circuit, and the other end of the resistor R9 is connected with pins 6 and 7 of the operational amplifier U2B; the grid electrode of the MOS transistor Q4 is connected with the resistor R20 and the resistor R25, and the source electrode of the MOS transistor Q4 is connected with the resistor R25;
one end of the resistor R19 is connected with the resistor R17, the capacitor C1, the capacitor C3 and the power output protection circuit, and the other end of the resistor R19 is grounded; the adjustable resistor R5 is connected with the power output protection circuit.
5. The VGA based constant power load apparatus of claim 1, wherein: the current sampling circuit comprises an operational amplifier U4A, a capacitor C11, a capacitor C14, a capacitor C15, a resistor R31, a resistor R32, a resistor R35 and a resistor R37;
one end of the resistor R32 is connected with the resistor R31 and the pin 3 of the operational amplifier U4A, and the other end of the resistor R is connected with the power output protection circuit; one end of the resistor R35 is connected with the resistor R37, the capacitor C15 and the pin 2 of the operational amplifier U4A, and the other end of the resistor R35 is connected with the power output protection circuit; one end of the capacitor C11 is connected with a pin 8 of the operational amplifier U4A, and the other end of the capacitor C is grounded; one end of the capacitor C14 is connected with a pin 4 of the operational amplifier U4A, and the other end of the capacitor C is grounded; and the pin 1 of the operational amplifier U4A is connected with the resistor R37, the capacitor C15 and the power control circuit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202223416135.5U CN218848215U (en) | 2022-12-20 | 2022-12-20 | VGA-based constant power load device |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202223416135.5U CN218848215U (en) | 2022-12-20 | 2022-12-20 | VGA-based constant power load device |
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| Publication Number | Publication Date |
|---|---|
| CN218848215U true CN218848215U (en) | 2023-04-11 |
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| CN202223416135.5U Active CN218848215U (en) | 2022-12-20 | 2022-12-20 | VGA-based constant power load device |
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2022
- 2022-12-20 CN CN202223416135.5U patent/CN218848215U/en active Active
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