A sampling comparison circuit for threshold adjustable overcurrent protection of a DC motor

Abstract

The utility model discloses a threshold adjustable direct current motor overcurrent protection's sampling comparison circuit belongs to direct current motor overcurrent protection circuit field, including sampling voltage dividing resistance module, comparator circuit and flip circuit, sampling voltage dividing resistance module one end is connected with external IPM drive circuit, and the other end of sampling voltage dividing resistance module is connected with the input of comparator circuit, the output of comparator circuit is connected with one end of flip circuit, and the other end of flip circuit is connected with external IPM drive circuit, sampling resistance module sampling resistance module includes sampling resistance module, voltage dividing resistance module, sampling resistance module, voltage dividing resistance module is connected with two input of comparator circuit respectively. The utility model accurate adaptation changeable working condition, real -time adjustment comparator reference voltage, increase security, through nimble dynamic threshold setting and accurate current monitoring, the reliability, adaptability and response speed of system have been improved significantly.

Description

Technical Field

[0001] This utility model relates to a DC motor overcurrent protection circuit, specifically a sampling comparison circuit for DC motor overcurrent protection with adjustable threshold. Background Technology

[0002] Currently, more and more household air conditioners are adopting full DC inverter technology, with both the compressor and fan using DC brushless motors, which have advantages such as energy saving, comfort, low noise, and wide voltage operating range. There are many models and brands of compressors and fans, and the demagnetization protection currents between different models usually vary. Therefore, when the air conditioner outdoor unit board drives different models of compressors or fans, it is necessary to change the parameters of relevant circuit components according to the different demagnetization protection currents of the motors. This results in different hardware boards, leading to a decrease in production efficiency and an increase in management costs.

[0003] Existing DC motor overcurrent protection circuits cannot accurately monitor the current required by different motors, affecting the adaptability of motor operation and impacting safety. Utility Model Content

[0004] To address the aforementioned problems in the prior art, the purpose of this invention is to provide a sampling comparison circuit for DC motor overcurrent protection with adjustable threshold, thereby solving the problems mentioned in the background art.

[0005] To achieve the above objectives, this utility model provides the following technical solution:

[0006] A sampling comparison circuit for overcurrent protection of a DC motor with adjustable threshold includes a sampling voltage divider resistor module, a comparator circuit, and a switching circuit; one end of the sampling voltage divider resistor module is connected to an external IPM drive circuit, and the other end of the sampling voltage divider resistor module is connected to the input terminal of the comparator circuit; the output terminal of the comparator circuit is connected to one end of the switching circuit, and the other end of the switching circuit is connected to the external IPM drive circuit.

[0007] The sampling resistor module includes a sampling resistor module and a voltage divider resistor module; the sampling resistor module and the voltage divider resistor module are respectively connected to the two input terminals of the comparator circuit.

[0008] As a further aspect of the present invention: the sampling resistor module consists of four sets of resistors connected in parallel, and the voltage divider resistor module is an adjustable voltage divider resistor R137.

[0009] As a further aspect of the present invention: the sampling resistor module includes resistors RS5, RS6, RS7, and RS8; one end of resistor RS5 is connected to the IPM driving circuit; the other end of resistor RS5 is connected to the ground terminal NGND.

[0010] As a further embodiment of the present invention: a resistor RS6 is connected in parallel across the two ends of the resistor RS5; a resistor RS7 is connected in parallel across the two ends of the resistor RS5; and a resistor RS8 is connected in parallel across the two ends of the resistor RS5.

[0011] As a further aspect of the present invention: the comparator circuit includes comparator IC4A; the negative input terminal of comparator IC4A is connected to one end of resistor R69, and the other end of resistor R69 is connected to one end of resistor RS5;

[0012] The negative input terminal of comparator IC4A is connected to one end of capacitor C62, and the other end of capacitor C62 is connected to ground NGND;

[0013] The positive input terminal of comparator IC4A is connected to one end of resistor R138, and the other end of resistor R138 is connected to the +5V power supply.

[0014] The positive input terminal of comparator IC4A is connected to one end of capacitor C87, and the other end of capacitor C87 is connected to ground NGND;

[0015] The output of comparator IC4A is connected to one end of resistor R136, and the other end of resistor R136 is connected to the +5V power supply.

[0016] As a further aspect of the present invention: the adjustable voltage divider resistor is an adjustable resistor R137, one end of which is connected to the ground terminal NGND; the other end of which is connected to the positive input terminal of comparator IC4A in the comparator circuit.

[0017] As a further aspect of the present invention: the power supply terminal of the comparator IC4A is connected to the +5V power supply; the ground terminal of the comparator IC4A is connected to the ground terminal NGND.

[0018] As a further aspect of the present invention: the ground terminal of the comparator IC4A is connected to one end of the capacitor C84, and the other end of the capacitor C84 is connected to the power supply terminal of the comparator IC4A.

[0019] As a further aspect of the present invention: the switching circuit includes transistor P2, resistor R12, resistor R56, resistor R7 and resistor R115;

[0020] The base of transistor P2 is connected to one end of resistor R12, and the other end of resistor R12 is connected to the output of comparator IC4A in the comparator circuit.

[0021] The emitter of transistor P2 is connected to the +5V power supply.

[0022] One end of resistor R56 is connected to the emitter of transistor P2, and the other end of resistor R56 is connected to the base of transistor P2.

[0023] The collector of transistor P2 is connected to one end of resistor R7, and the other end of resistor R7 is connected to ground terminal NGND.

[0024] The collector of transistor P2 is connected to one end of resistor R115, and the other end of resistor R115 is connected to the IPM drive circuit.

[0025] As a further embodiment of the present invention: the other end of the resistor R115 is connected to one end of the capacitor C103, and the other end of the capacitor C103 is connected to the ground terminal NGND.

[0026] Compared with the prior art, the beneficial effects of this utility model are:

[0027] This invention precisely adapts to various operating conditions, adjusts the comparator reference voltage in real time, and adapts to different current scenarios such as motor start-up, stall, and full load. It simplifies system design complexity, operates independently of the MCU, and increases safety. Through flexible dynamic threshold settings and precise current monitoring, it significantly improves the system's reliability, adaptability, and response speed. Attached Figure Description

[0028] Figure 1 This is a circuit diagram of a sampling comparison circuit for overcurrent protection of a DC motor with adjustable threshold disclosed in an embodiment. Detailed Implementation

[0029] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present utility model.

[0030] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installed," "equipped with," "connected," and "linked" should be interpreted broadly; for example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0031] Please see Figure 1A sampling comparison circuit for overcurrent protection of a DC motor with adjustable threshold includes a sampling voltage divider resistor module, a comparator circuit, and a switching circuit; one end of the sampling voltage divider resistor module is connected to an external IPM drive circuit, and the other end of the sampling voltage divider resistor module is connected to the input terminal of the comparator circuit; the output terminal of the comparator circuit is connected to one end of the switching circuit, and the other end of the switching circuit is connected to the external IPM drive circuit.

[0032] The sampling resistor module includes a sampling resistor module and a voltage divider resistor module; the sampling resistor module and the voltage divider resistor module are respectively connected to the two input terminals of the comparator circuit.

[0033] The current sampling resistor obtains the sampling voltage through the current flowing through the DC motor and connects the sampling voltage to the inverting input of the comparator; the inverting input of the comparator is the sampling voltage, and the non-inverting input is the voltage divided by two voltage divider resistors. The output signal of the comparator is connected to the base of the transistor; the base is connected to the output signal of the comparator, and the collector signal is connected to the IPM drive circuit.

[0034] The sampling resistor module consists of four sets of resistors connected in parallel, and the voltage divider resistor module is an adjustable voltage divider resistor R137.

[0035] The sampling resistor module includes resistors RS5, RS6, RS7, and RS8; one end of resistor RS5 is connected to the IPM drive circuit; the other end of resistor RS5 is connected to the ground terminal NGND.

[0036] Resistor RS6 is connected in parallel across resistor RS5; resistor RS7 is connected in parallel across resistor RS5; resistor RS8 is connected in parallel across resistor RS5.

[0037] The adjustable voltage divider resistor is an adjustable resistor R137. One end of the adjustable resistor R137 is connected to the ground terminal NGND; the other end of the adjustable resistor R137 is connected to the positive input terminal of comparator IC4A.

[0038] The comparator circuit includes comparator IC4A; the negative input terminal of comparator IC4A is connected to one end of resistor R69, and the other end of resistor R69 is connected to one end of resistor RS5;

[0039] The negative input terminal of comparator IC4A is connected to one end of capacitor C62, and the other end of capacitor C62 is connected to ground NGND;

[0040] The positive input terminal of comparator IC4A is connected to one end of resistor R138, and the other end of resistor R138 is connected to the +5V power supply.

[0041] The positive input terminal of comparator IC4A is connected to one end of capacitor C87, and the other end of capacitor C87 is connected to ground NGND;

[0042] The output of comparator IC4A is connected to one end of resistor R136, and the other end of resistor R136 is connected to the +5V power supply.

[0043] The power supply terminal of comparator IC4A is connected to the +5V power supply; the ground terminal of comparator IC4A is connected to the ground terminal NGND.

[0044] The ground terminal of comparator IC4A is connected to one end of capacitor C84, and the other end of capacitor C84 is connected to the power supply terminal of comparator IC4A.

[0045] The sampling voltages on current sampling resistors RS5, RS6, RS7, and RS8 are connected to the inverting input of comparator IC4A. (RS5 / / RS6 / / RS7 / / RS8) * DC motor drive current = sampling voltage. The non-inverting input of IC4A is the voltage divider signal from resistor R138 and adjustable resistor R137. The resistance of adjustable resistor R137 can be changed by manually rotating the knob on R137, thus changing the voltage at the non-inverting input of comparator IC4A. When the divided voltage is greater than the sampling voltage, comparator IC4A outputs a high level; when the divided voltage is less than the sampling voltage, comparator IC4A outputs a low level.

[0046] The switching circuit includes transistor P2, resistor R12, resistor R56, resistor R7, and resistor R115;

[0047] The base of transistor P2 is connected to one end of resistor R12, and the other end of resistor R12 is connected to the output of comparator IC4A in the comparator circuit.

[0048] The emitter of transistor P2 is connected to the +5V power supply.

[0049] One end of resistor R56 is connected to the emitter of transistor P2, and the other end of resistor R56 is connected to the base of transistor P2.

[0050] The collector of transistor P2 is connected to one end of resistor R7, and the other end of resistor R7 is connected to ground terminal NGND.

[0051] The collector of transistor P2 is connected to one end of resistor R115, and the other end of resistor R115 is connected to the IPM drive circuit.

[0052] One end of capacitor C103 is connected to the other end of resistor R115, and the other end of capacitor C103 is connected to ground terminal NGND.

[0053] The connection point between resistor RS5 and the IPM drive circuit is the N (UVW) pin of the IPM drive circuit. The other end of resistor R115 is connected to the CIN pin of the IPM drive circuit. The drive current of the DC motor is sampled through current sampling resistors RS5, RS6, RS7 and RS8. The sampled voltage is connected to the inverting input of the comparator. The output signal of the comparator is connected to the base of the transistor switching circuit. The collector of the transistor switching circuit is connected to the CIN pin of the IPM drive circuit.

[0054] The output signal of comparator IC4A is connected to the base of the transistor switching circuit. When the output signal of comparator IC4A is high, transistor P2 is turned off, and the CIN pin of the IPM driver circuit is pulled down to GND through resistor R7, so the voltage of CIN of the IPM driver circuit is low. When the output signal of comparator IC4A is low, transistor P2 is turned on, and the voltage of CIN of the IPM driver circuit is +5V.

[0055] Therefore, by rotating the knob of the adjustable resistor R137 to change its resistance value, the voltage division voltage of the adjustable resistor R137 and resistor R138 can be changed, thereby enabling a single computer board hardware to cope with DC motors at different demagnetization current points.

[0056] The threshold-adjustable DC motor overcurrent protection sampling comparator circuit significantly improves system reliability, adaptability, and response speed through flexible dynamic threshold settings and precise current monitoring. This invention accurately adapts to varying operating conditions, adjusting the comparator reference voltage in real time to accommodate different current scenarios such as motor start-up, stall, and full load. It simplifies system design complexity, operates independently of the MCU, increases safety, and facilitates practical application.

[0057] It will be apparent to those skilled in the art that this invention is not limited to the details of the exemplary embodiments described above, and that it can be implemented in other specific forms without departing from the spirit or essential characteristics of this invention. Therefore, the embodiments should be considered exemplary and not restrictive in all respects. The scope of this invention is defined by the appended claims rather than the foregoing description, and therefore all variations falling within the meaning and scope of equivalents of the claims are intended to be included within this invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0058] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A sampling comparison circuit for overcurrent protection of a DC motor with adjustable threshold, characterized in that, It includes a sampling voltage divider resistor module, a comparator circuit, and a switching circuit; one end of the sampling voltage divider resistor module is connected to an external IPM driver circuit, and the other end of the sampling voltage divider resistor module is connected to the input terminal of the comparator circuit; the output terminal of the comparator circuit is connected to one end of the switching circuit, and the other end of the switching circuit is connected to the external IPM driver circuit. The sampling resistor module includes a sampling resistor module and a voltage divider resistor module; the sampling resistor module and the voltage divider resistor module are respectively connected to the two input terminals of the comparator circuit.

2. The sampling and comparison circuit for threshold-adjustable DC motor overcurrent protection according to claim 1, characterized in that, The sampling resistor module consists of four sets of resistors connected in parallel, and the voltage divider resistor module is an adjustable voltage divider resistor R137.

3. The sampling and comparison circuit for overcurrent protection of a DC motor with adjustable threshold as described in claim 2, characterized in that, The sampling resistor module includes resistors RS5, RS6, RS7, and RS8; one end of resistor RS5 is connected to the IPM drive circuit; the other end of resistor RS5 is connected to the ground terminal NGND.

4. The sampling and comparison circuit for threshold-adjustable DC motor overcurrent protection according to claim 3, characterized in that, A resistor RS6 is connected in parallel across the two ends of the resistor RS5; a resistor RS7 is connected in parallel across the two ends of the resistor RS5; and a resistor RS8 is connected in parallel across the two ends of the resistor RS5.

5. The sampling and comparison circuit for overcurrent protection of a DC motor with adjustable threshold as described in claim 4, characterized in that, The comparator circuit includes comparator IC4A; the negative input terminal of comparator IC4A is connected to one end of resistor R69, and the other end of resistor R69 is connected to one end of resistor RS5. The negative input terminal of comparator IC4A is connected to one end of capacitor C62, and the other end of capacitor C62 is connected to ground NGND; The positive input terminal of comparator IC4A is connected to one end of resistor R138, and the other end of resistor R138 is connected to the +5V power supply. The positive input terminal of comparator IC4A is connected to one end of capacitor C87, and the other end of capacitor C87 is connected to ground NGND; The output of comparator IC4A is connected to one end of resistor R136, and the other end of resistor R136 is connected to the +5V power supply.

6. The sampling and comparison circuit for threshold-adjustable DC motor overcurrent protection according to claim 5, characterized in that, The adjustable voltage divider resistor is an adjustable resistor R137. One end of the adjustable resistor R137 is connected to the ground terminal NGND; the other end of the adjustable resistor R137 is connected to the positive input terminal of comparator IC4A in the comparator circuit.

7. The sampling and comparison circuit for threshold-adjustable DC motor overcurrent protection according to claim 6, characterized in that, The power supply terminal of the comparator IC4A is connected to a +5V power supply; The ground terminal of comparator IC4A is connected to the ground terminal NGND.

8. The sampling and comparison circuit for threshold-adjustable DC motor overcurrent protection according to claim 7, characterized in that, The ground terminal of the comparator IC4A is connected to one end of the capacitor C84, and the other end of the capacitor C84 is connected to the power supply terminal of the comparator IC4A.

9. The sampling and comparison circuit for threshold-adjustable DC motor overcurrent protection according to claim 8, characterized in that, The aforementioned switching circuit includes transistor P2, resistor R12, resistor R56, resistor R7, and resistor R115; The base of transistor P2 is connected to one end of resistor R12, and the other end of resistor R12 is connected to the output of comparator IC4A in the comparator circuit. The emitter of transistor P2 is connected to the +5V power supply. One end of resistor R56 is connected to the emitter of transistor P2, and the other end of resistor R56 is connected to the base of transistor P2. The collector of transistor P2 is connected to one end of resistor R7, and the other end of resistor R7 is connected to ground terminal NGND. The collector of transistor P2 is connected to one end of resistor R115, and the other end of resistor R115 is connected to the IPM drive circuit.

10. The sampling and comparison circuit for overcurrent protection of a DC motor with adjustable threshold as described in claim 9, characterized in that, The other end of the resistor R115 is connected to one end of the capacitor C103, and the other end of the capacitor C103 is connected to the ground terminal NGND.

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