CN212649385U - Direct current motor control circuit and direct current motor control system - Google Patents

Abstract

The embodiment of the utility model provides a motor control technology field is related to, a DC motor control circuit and DC motor control system are provided. The method comprises the following steps: a controller for transmitting a PWM signal; the speed regulation control circuit is electrically connected with the controller and used for responding to the PWM signal and generating a driving power supply, and the driving power supply is in direct proportion to the duty ratio of the PWM signal; the H-bridge driving circuit is electrically connected with the speed regulation control circuit and used for driving the direct current motor to work according to a driving power supply, and the driving power supply is in direct proportion to the rotating speed of the direct current motor; the overcurrent protection circuit is electrically connected with the H-bridge drive circuit and the speed regulation control circuit and is used for triggering the speed regulation control circuit to reduce the drive power supply when detecting that the drive current flowing through the direct current motor is greater than or equal to the threshold current; and the rotating speed detection circuit is respectively electrically connected with the H-bridge drive circuit and the controller and is used for sampling the working voltage of the direct current motor. The embodiment of the utility model provides a can promote DC motor control circuit's security and reliability.

Description

Direct current motor control circuit and direct current motor control system

[ technical field ] A method for producing a semiconductor device

The embodiment of the utility model provides a relate to motor control technical field, especially relate to a direct current motor control circuit and direct current motor control system.

[ background of the invention ]

At present, an H-bridge driving circuit is mostly adopted to control the operation of a direct current motor, the H-bridge driving circuit is electrically connected with a controller, and the bias of a target switch tube base electrode or a grid electrode of the H-bridge driving circuit is modulated through the duty ratio of a PWM signal output by the controller, so that the conduction time of the target switch tube is changed, a driving power supply is obtained, and the forward or reverse speed regulation of the direct current motor is realized. However, in the process of switching the operating state of the target switching tube, the modulation of the PWM signal may be affected, which may reduce the reliability of the driving power supply, and in the process of adjusting the speed of the dc motor, the driving power supply is constant, and when the driving current for driving the dc motor is greater than or equal to the threshold current, a safety hazard such as circuit fire may be caused.

[ Utility model ] content

The embodiment of the utility model provides a aim at providing a safe and reliable's DC motor control circuit and DC motor control system.

In order to solve the above technical problem, an embodiment of the present invention provides the following technical solution:

the embodiment of the utility model provides a direct current motor control circuit, include:

a controller for transmitting a PWM signal;

the speed regulation control circuit is electrically connected with the controller and used for responding to the PWM signal and generating a driving power supply, and the driving power supply and the duty ratio of the PWM signal are in a direct proportion relation;

the H-bridge driving circuit is electrically connected with the speed regulation control circuit and used for driving the direct current motor to work according to the driving power supply, and the driving power supply is in direct proportion to the rotating speed of the direct current motor;

the overcurrent protection circuit is respectively electrically connected with the H-bridge drive circuit and the speed regulation control circuit and is used for sending a protection signal to the speed regulation control circuit when detecting that the drive current flowing through the direct current motor is greater than or equal to a threshold current, so that the speed regulation control circuit reduces the drive power supply; and the number of the first and second groups,

and the rotating speed detection circuit is respectively electrically connected with the H-bridge driving circuit and the controller and is used for sampling the working voltage of the direct current motor and sending the working voltage to the controller, so that the controller controls the speed regulation control circuit to regulate the driving power supply.

Optionally, the speed control circuit includes:

a charging circuit;

and the starting circuit is respectively electrically connected with the controller and the charging circuit and used for controlling an external power supply to charge the charging circuit and provide the driving power supply for the H-bridge driving circuit when the PWM signal is at a high level, and controlling the external power supply to stop charging the charging circuit when the PWM signal is at a low level so that the charging circuit discharges to provide the driving power supply for the H-bridge driving circuit.

Optionally, the starting circuit includes a first resistor, a second resistor, an NPN transistor, a third resistor, a fourth resistor, and a PNP transistor;

one end of the first resistor is used for receiving the PWM signal, and the other end of the first resistor is electrically connected with one end of the second resistor, the base electrode of the NPN triode and the overcurrent protection circuit; the other end of the second resistor is grounded; an emitting electrode of the NPN triode is grounded, and a collector electrode of the NPN triode is electrically connected with one end of the third resistor; the other end of the third resistor is electrically connected with one end of the fourth resistor and the base electrode of the PNP triode; the other end of the fourth resistor is electrically connected with an emitting electrode of the PNP triode and used for receiving an external power supply; and the collector electrode of the PNP triode is electrically connected with the charging circuit.

Optionally, the charging circuit comprises an inductor and a first capacitor;

one end of the inductor is electrically connected with the collector of the PNP triode, and the other end of the inductor is electrically connected with the positive electrode of the first capacitor and used for outputting the driving power supply; and the negative electrode of the first capacitor is grounded.

Optionally, the speed regulation control circuit further includes a follow current circuit, and the follow current circuit is electrically connected between the starting circuit and the charging circuit, and is configured to control, when the PWM signal is at a low level, the starting circuit to stop charging the charging circuit by an external power supply, and perform follow current processing on the back electromotive force generated by the charging circuit.

Optionally, the freewheel circuit comprises a first diode and a second diode;

the cathode of the first diode is electrically connected with the emitting electrode of the PNP triode, and the anode of the first diode is electrically connected with the collector electrode of the PNP triode, one end of the inductor and the cathode of the second diode; the anode of the second diode is grounded.

Optionally, the over-current protection circuit includes:

the first sampling circuit is electrically connected with the H-bridge driving circuit and is used for sampling the driving current flowing through the direct current motor and generating sampling voltage;

and the switching circuit is respectively electrically connected with the first sampling circuit and the speed regulation control circuit and is used for biasing the PWM signal at a low level serving as the protection signal when the sampling voltage is greater than a voltage conduction threshold value, so that the speed regulation control circuit reduces the driving power supply.

Optionally, the first sampling circuit includes a fifth resistor, a second capacitor, and a sixth resistor;

one end of the fifth resistor is electrically connected with the H-bridge driving circuit, and the other end of the fifth resistor is electrically connected with one end of the second capacitor, one end of the sixth resistor and the switch circuit; the other end of the second capacitor is grounded; the other end of the sixth resistor is grounded.

Optionally, the rotation speed detection circuit includes a seventh resistor, an eighth resistor, and a third capacitor;

one end of the seventh resistor is electrically connected with the H-bridge driving circuit and one end of the eighth resistor, and the other end of the seventh resistor is grounded; the other end of the eighth resistor is electrically connected with one end of the third capacitor and the controller; the other end of the third capacitor is grounded.

The embodiment of the utility model provides a still provide a DC motor control system, include:

a direct current motor;

the dc motor control circuit of any preceding claim, electrically connected to the dc motor.

The utility model has the advantages that: compared with the prior art, the embodiment of the utility model provides a direct current motor control circuit and direct current motor control system, the PWM signal that sends through speed governing control circuit response controller, produce drive power supply, drive power supply and PWM signal's duty ratio proportional relation, H bridge drive circuit is according to drive power supply drive direct current motor work, drive power supply and direct current motor's rotational speed proportional relation, overcurrent protection circuit is when detecting the drive current of flowing through direct current motor and being greater than or equal to threshold current, send protection signal to speed governing control circuit, make speed governing control circuit reduce drive power supply. Therefore, the embodiment of the utility model provides a convert PWM signal into drive power supply through speed governing control circuit to direct drive direct current motor, and when detecting the drive current of flowing through direct current motor when being more than or equal to threshold current through overcurrent protection circuit, make speed governing control circuit reduce drive power supply, in order to realize instant hardware protection, thereby promoted direct current motor control circuit's security and reliability.

[ description of the drawings ]

One or more embodiments are illustrated by way of example in the accompanying drawings, which correspond to the figures in which like reference numerals refer to similar elements and which are not to scale unless otherwise specified.

Fig. 1 is a schematic circuit structure diagram of a dc motor control system according to an embodiment of the present invention;

fig. 2 is a schematic circuit diagram of a dc motor control circuit according to an embodiment of the present invention;

fig. 3 is a schematic circuit diagram of a dc motor control circuit according to an embodiment of the present invention;

fig. 4 is a schematic circuit connection diagram of a speed regulation control circuit according to an embodiment of the present invention;

fig. 5 is a schematic circuit connection diagram of an H-bridge driving circuit according to an embodiment of the present invention;

fig. 6 is a schematic circuit connection diagram of an overcurrent protection circuit according to an embodiment of the present invention;

fig. 7 is a schematic circuit connection diagram of a rotation speed detection circuit according to an embodiment of the present invention.

[ detailed description ] embodiments

To facilitate an understanding of the present application, the present application is described in more detail below with reference to the accompanying drawings and detailed description. It will be understood that when an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may be present. Furthermore, the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

In addition, the technical features mentioned in the different embodiments of the present application described below may be combined with each other as long as they do not conflict with each other.

Fig. 1 is a schematic circuit diagram of a dc motor control system according to an embodiment of the present invention. As shown in fig. 1, the dc motor control system 300 includes a dc motor 200 and a dc motor control circuit 100 according to any embodiment, wherein the dc motor control circuit 100 is electrically connected to the dc motor 200 for controlling the operation of the dc motor 200.

Please refer to fig. 2, which is a schematic circuit diagram of a dc motor control circuit according to an embodiment of the present invention. As shown in fig. 2, the dc motor control circuit 100 includes a controller 10, a speed control circuit 20, an H-bridge drive circuit 30, an overcurrent protection circuit 40, and a rotation speed detection circuit 50.

The controller 10 is used to send PWM signals.

In the embodiment of the present invention, the controller 10 includes an AD sampling port and a plurality of IO ports, the AD sampling port is used for collecting the operating voltage of the dc motor 200 (such as the AD port shown in fig. 7), and the plurality of IO ports include the AD sampling port used for outputting the PWM signal, the DR1 level signal and the DR2 level signal (specifically shown in fig. 4 and fig. 5). The PWM signal controls the on-off of the switching device of the inverter circuit, so that a series of pulses with equal amplitude are obtained at the output end, and the pulses are used for replacing sine waves or required waveforms. Therefore, the PWM signal is a digital signal, specifically an ON or OFF repetitive pulse train, and PWM signals with different duty ratios can be obtained by controlling the ON (ON) or OFF (OFF) ratio.

The embodiment of the utility model provides an in, controller 10 includes the singlechip, and the singlechip can adopt 51 series, Arduino series, STM32 series etc.. In some embodiments, the controller 10 may also be a general purpose processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA), an ARM (Acorn RISC machine) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination of these components; but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine; or as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

The speed control circuit 20 is electrically connected to the controller 10 and configured to generate a driving power in response to the PWM signal, where the driving power is in direct proportion to a duty ratio of the PWM signal.

Referring to fig. 3, the speed control circuit 20 includes a charging circuit 201 and a starting circuit 202.

As shown in fig. 4, the charging circuit 201 includes an inductor L1 and a first capacitor C1. One end of the inductor L1 is electrically connected with a collector Q2 of the PNP triode, and the other end of the inductor L1 is electrically connected with the anode of the first capacitor C1 and used for outputting a driving power supply V2; the cathode of the first capacitor C1 is connected to ground.

The start circuit 202 is electrically connected to the controller 10 and the charging circuit 201, and is configured to control the external power source to charge the charging circuit 201 and provide the driving power source for the H-bridge driving circuit 30 when the PWM signal is at a high level, and control the external power source to stop charging the charging circuit 201 when the PWM signal is at a low level, so that the charging circuit 201 discharges to provide the driving power source for the H-bridge driving circuit 30.

As shown in fig. 4, the start circuit includes a first resistor R1, a second resistor R2, an NPN transistor Q1, a third resistor R3, a fourth resistor R4, and a PNP transistor Q2. One end of the first resistor R1 is configured to receive a PWM signal, and the other end of the first resistor R1 is electrically connected to one end of the second resistor R2, the base of the NPN transistor Q1, and the overcurrent protection circuit 40 (through a network port P shown in fig. 4 and the overcurrent protection circuit 40, the network port P is a connection node of the first resistor R1, the second resistor R2, and the NPN transistor Q1); the other end of the second resistor R2 is grounded; an emitter of the NPN triode Q1 is grounded, and a collector of the NPN triode Q1 is electrically connected to one end of the third resistor R3; the other end of the third resistor R3 is electrically connected with one end of the fourth resistor R4 and the base electrode of the PNP triode Q2; the other end of the fourth resistor R4 is electrically connected with an emitter of a PNP triode Q2 and used for receiving an external power supply V1; the collector of the PNP transistor Q2 is electrically connected to the charging circuit 201 (i.e., one end of the inductor L1).

In some embodiments, referring to fig. 3 again, the speed control circuit 20 further includes a freewheel circuit 203, and the freewheel circuit 203 is electrically connected between the start circuit 202 and the charging circuit 201, and is used for performing freewheel processing on the back electromotive force generated by the charging circuit 201 when the start circuit 202 controls the external power supply to stop charging the charging circuit 201 when the PWM signal is at the low level.

As shown in fig. 4, the freewheel circuit 203 includes a first diode D1 and a second diode D2. The cathode of the first diode D1 is electrically connected with the emitter of the PNP triode Q2, and the anode of the first diode D1 is electrically connected with the collector of the PNP triode Q2, one end of the inductor L1 and the cathode of the second diode D2; the anode of the second diode D2 is grounded.

In summary, the operation process of the speed control circuit 20 is as follows:

(1) receiving the PWM signal sent by the controller 10, when the PWM signal is at a high level, the high level signal reaches the base of the NPN transistor Q1 through the first resistor R1, meeting the conduction condition of the NPN transistor Q1, the NPN transistor Q1 is turned on, the collector voltage of the NPN transistor Q1 is pulled low, at this time, meeting the conduction condition of the PNP transistor Q2, the PNP transistor Q2 is turned on, and the external power supply V1 charges the first capacitor C1 and supplies power to the H-bridge driving circuit 30 through the emitter of the PNP transistor Q2, the collector of the PNP transistor Q2, and the inductor L1.

(2) When the PWM signal is at a low level, the low level signal reaches the base of the NPN transistor Q1 through the first resistor R1, the on condition of the NPN transistor Q1 is not satisfied, the NPN transistor Q1 is turned off, and at this time, the on condition of the PNP transistor Q2 is not satisfied, and the PNP transistor Q2 is turned off. At this time, the first capacitor C1 discharges to allow the stored energy to power the H-bridge driver circuit 30. Meanwhile, due to the characteristic that the current passing through the inductor cannot change abruptly, the back electromotive force generated by the inductor L1 freewheels through the first diode D1 and the second diode D2 to protect the PNP transistor Q2 from breakdown.

(3) Repeating the steps (1) and (2) according to the periodic variation of the PWM signal, the speed control circuit 20 converts the external power source V1 into the driving power source V2, the magnitude of the driving power source V2 is in direct proportion to the duty ratio of the PWM signal, the larger the duty ratio of the PWM signal is, the larger the driving power source V2 output by the speed control circuit 20 is, and the smaller the duty ratio of the PWM signal is, the smaller the driving power source V2 output by the speed control circuit 20 is.

The H-bridge driving circuit 30 is electrically connected to the speed control circuit 20, and is configured to drive the dc motor 200 to operate according to a driving power, where the driving power is in direct proportion to the rotation speed of the dc motor 200.

As shown in fig. 5, the H-bridge driving circuit 30 includes a PMOS transistor TR1, a PMOS transistor TR2, an NMOS transistor TR3, an NMOS transistor TR4, a resistor R51, a resistor R52, an NPN transistor Q51, a resistor R53, a resistor R54, a resistor R55, a resistor R56, an NPN transistor Q52, a resistor R57, a resistor R58, a resistor R59, a resistor R60, a resistor R61, and a resistor R62.

The source of the PMOS transistor TR1 is electrically connected to one end of the resistor R54, the source of the PMOS transistor TR2, one end of the resistor R58 and the speed control circuit 20, and is configured to receive a driving power V2, the drain of the PMOS transistor TR1 is electrically connected to the drain of the NMOS transistor TR3 and the positive electrode M + of the dc motor 200, and the gate of the PMOS transistor TR1 is electrically connected to the other end of the resistor R54 and one end of the resistor R53; the drain electrode of the PMOS tube TR2 is electrically connected with the drain electrode of the NMOS tube TR4 and the cathode M-of the direct current motor 200, and the grid electrode of the PMOS tube TR2 is electrically connected with the other end of the resistor R58 and one end of the resistor R57; the source electrode of the NMOS tube TR3 is electrically connected with the source electrode of the NMOS tube TR4 and is electrically connected with the overcurrent protection circuit 40 and the rotating speed detection circuit 50 through a network port IU, and the grid electrode of the NMOS tube TR3 is electrically connected with one end of the resistor R59 and one end of the resistor R60; the gate of the NMOS transistor TR4 is electrically connected to one end of the resistor R61 and one end of the resistor R62; one end of the resistor R51 is electrically connected with the controller 10 and is used for receiving DR1 level signals, and the other end of the resistor R51 is electrically connected with one end of the resistor R52 and the base electrode of the NPN triode Q51; the other end of the resistor R52 is grounded; an emitting electrode of the NPN triode Q51 is grounded, and a collecting electrode of the NPN triode Q51 is electrically connected with the other end of the resistor R53; one end of the resistor R55 is electrically connected with the controller 10 and is used for receiving DR2 level signals, and the other end of the resistor R55 is electrically connected with one end of the resistor R56 and the base electrode of the NPN triode Q52; the other end of the resistor R56 is grounded; an emitting electrode of the NPN triode Q52 is grounded, and a collecting electrode of the NPN triode Q52 is electrically connected with the other end of the resistor R57; the other end of the resistor R59 is electrically connected with the other end of the resistor R61; the other end of the resistor R60 is grounded; the other end of the resistor R62 is connected to ground.

When the DR1 level signal is at a high level and the DR2 level signal is at a low level, the high level signal reaches the base electrode of the NPN triode Q51 through the resistor R51, the conduction condition of the NPN triode Q51 is met, the NPN triode Q51 is turned on, the collector voltage of the NPN triode Q51 is pulled down, the gate of the PMOS transistor TR1 is at a low voltage, the conduction condition of the PMOS transistor TR1 is met, and the PMOS transistor TR1 is turned on; meanwhile, a high-level signal reaches the grid electrode of the NMOS tube TR4 through the resistor R61, the conduction condition of the NMOS tube TR4 is met, and the NMOS tube TR4 is conducted; the low-level signal reaches the base electrode of an NPN triode Q52 through a resistor R55, the conducting condition of the NPN triode Q52 is not met, the NPN triode Q52 is cut off, the conducting condition of a PMOS tube TR2 is not met, and the PMOS tube TR2 is cut off; meanwhile, a low-level signal reaches the gate of the NMOS transistor TR3 through the resistor R59, the on condition of the NMOS transistor TR3 is not met, and the NMOS transistor TR3 is turned off, so that the driving power supply V2 passes through the PMOS transistor TR1, the positive pole M + of the dc motor 200, the negative pole M-of the dc motor 200, and the NMOS transistor TR4 to the ground, and the dc motor 200 rotates forward.

When the DR1 level signal is at a low level and the DR2 level signal is at a high level, the low level signal reaches the base electrode of an NPN triode Q51 through a resistor R51, the conduction condition of the NPN triode Q51 is not met, the NPN triode Q51 is cut off, the conduction condition of a PMOS tube TR1 is not met, and the PMOS tube TR1 is cut off; meanwhile, a low-level signal reaches the grid electrode of the NMOS tube TR4 through the resistor R61, the on-state condition of the NMOS tube TR4 is not met, and the NMOS tube TR4 is cut off; the high-level signal reaches the base electrode of an NPN triode Q52 through a resistor R55, the conducting condition of an NPN triode Q52 is met, the NPN triode Q52 is conducted, the voltage of the collector electrode of the NPN triode Q52 is pulled down, the grid voltage of a PMOS tube TR2 is low voltage, the conducting condition of a PMOS tube TR2 is met, and the PMOS tube TR2 is conducted; meanwhile, a low-level signal reaches the gate of the NMOS transistor TR3 through the resistor R59, the conduction condition of the NMOS transistor TR3 is met, and the NMOS transistor TR3 is turned on, so that the driving power supply V2 passes through the PMOS transistor TR2, the negative electrode M of the dc motor 200, the positive electrode M of the dc motor 200, and the NMOS transistor TR3 to the ground, and the dc motor 200 is reversed.

In summary, during the forward rotation or the reverse rotation of the dc motor 200, the magnitude of the driving power V2 is in direct proportion to the rotation speed of the dc motor 200, and the larger the driving power V2, the faster the rotation speed of the dc motor 200, and the smaller the driving power V2, the slower the rotation speed of the dc motor 200. Therefore, the rotating speed of the dc motor 200 is related to the duty ratio of the PWM signal, but the PWM signal does not directly participate in the speed regulation process of the dc motor 200, thereby avoiding the problem that the PWM signal directly acts on the H-bridge driving circuit 30, which causes the unreliable output driving power due to the on and off of the semiconductor switching device.

The overcurrent protection circuit 40 is electrically connected to the H-bridge driving circuit 30 and the speed control circuit 20, and is configured to send a protection signal to the speed control circuit 20 when detecting that the driving current flowing through the dc motor 200 is greater than or equal to the threshold current, so that the speed control circuit 20 reduces the driving power supply.

As shown in fig. 3, the overcurrent protection circuit 40 includes a first sampling circuit 401 and a switching circuit 402.

The first sampling circuit 401 is electrically connected to the H-bridge driving circuit 30, and is configured to sample a driving current flowing through the dc motor 200 to generate a sampling voltage.

As shown in fig. 6, the first sampling circuit 401 includes a fifth resistor R5, a second capacitor C2, and a sixth resistor R6. One end of the fifth resistor R5 is electrically connected to the H-bridge driving circuit 30 (i.e., the network port IU shown in fig. 4), and the other end of the fifth resistor R5 is electrically connected to one end of the second capacitor C2, one end of the sixth resistor R6, and the switch circuit 402; the other end of the second capacitor C2 is grounded; the other end of the sixth resistor R6 is connected to ground.

The switching circuit 402 is electrically connected to the first sampling circuit 401 and the speed control circuit 20, respectively, and is configured to bias the PWM signal at a low level as a protection signal when the sampling voltage is greater than the voltage conduction threshold, so that the speed control circuit 20 reduces the driving power supply.

As shown in fig. 6, the switch circuit 402 includes an NPN transistor Q3, a base of the NPN transistor Q3 is electrically connected to the other end of the fifth resistor R5, one end of the second capacitor C2, and one end of the sixth resistor R6, an emitter of the NPN transistor Q3 is grounded, and a collector of the NPN transistor Q3 is electrically connected to the speed control circuit 20 (i.e., the network port P shown in fig. 4).

In summary, the operation of the over-current protection circuit 40 is as follows:

(1) assuming that the threshold current of the dc motor 200 is Im and the on-state voltage at the base of the NPN transistor Q3 is VB, when the dc motor 200 normally operates, the driving current of the dc motor 200 is smaller than the threshold current Im, and the driving current of the dc motor 200 passes through the fifth resistor R5, the second capacitor C2, and the sixth resistor R6 to generate a sampling voltage, and acts on the base of the NPN transistor Q3. At this time, the sampling voltage is lower than the on-state voltage VB of the base of the NPN transistor Q3, and the NPN transistor Q3 is not satisfied, and the NPN transistor Q3 is turned off, and the overcurrent protection circuit 40 does not operate.

(2) When the dc motor 200 is abnormal (e.g., a fault such as an arm short circuit or a short circuit of the dc motor 200 occurs), the driving current of the dc motor 200 is greater than or equal to the threshold current Im, and the driving current of the dc motor 200 passes through the fifth resistor R5, the second capacitor C2, and the sixth resistor R6 to generate a sampling voltage. At this time, the sampling voltage is greater than or equal to the conduction voltage VB of the base of the NPN transistor Q3, the conduction condition of the NPN transistor Q3 is satisfied, the NPN transistor Q3 is turned on, and the overcurrent protection circuit 40 operates. Specifically, when the NPN transistor Q3 is turned on, the voltage at the conductive collector of the NPN transistor Q3 is pulled low, and the base input of the NPN transistor Q1 is biased to a low level through the network port P, so that the speed control circuit 20 cannot receive the PWM signal, and the driving power supply V2 output by the speed control circuit 20 is lowered.

(3) When the driving power supply V2 drops to a level that the driving current of the dc motor 200 is smaller than the threshold current Im again, the step (1) is repeated, the overcurrent protection circuit 40 does not operate, so that the speed regulation control circuit 20 can normally receive the PWM signal again, and further the driving power supply V2 output by the speed regulation control circuit 20 is raised, and when the driving power supply V2 is raised to a level that the sampling voltage is greater than or equal to the conduction voltage VB of the base of the NPN triode Q3, the step (2) is repeated, and the overcurrent protection circuit 40 operates.

It should be noted that the above-mentioned process is a current amplification process of the NPN triode Q3, and finally, the driving current of the H-bridge driving circuit 30 (i.e., the driving current flowing through the dc motor 200) is equal to the threshold current Im, so that the driving current does not exceed the threshold current Im, and the purpose of protecting the H-bridge driving circuit 30 is achieved, thereby improving the safety of the dc motor control circuit 100.

The rotation speed detection circuit 50 is electrically connected to the H-bridge driving circuit and the controller, respectively, and is configured to sample a working voltage of the dc motor 200 and send the working voltage to the controller 10, so that the controller 10 controls the speed control circuit 20 to adjust the driving power.

As shown in fig. 7, the rotation speed detecting circuit 50 includes a seventh resistor R7, an eighth resistor R8, and a third capacitor C3. One end of the seventh resistor R7 is electrically connected to the H-bridge driving circuit 30 and one end of the eighth resistor R8, and the other end of the seventh resistor R7 is grounded; the other end of the eighth resistor R8 is electrically connected with one end of the third capacitor C3 and the controller 10; the other terminal of the third capacitor C3 is connected to ground.

The seventh resistor R7 is a sampling resistor, and the resistance of the seventh resistor R7 is equal to VB/Im. The eighth resistor R8 and the third capacitor C3 form a filter circuit, which performs noise reduction and filtering on the working voltage sampled by the seventh resistor R7 and sends the working voltage to an AD sampling port of the controller 10, and the controller 10 calculates a target duty ratio of the PWM signal according to the working voltage sampled by the rotation speed detection circuit 50 and a preset voltage, so that the speed regulation control circuit 20 adjusts the driving power supply according to the target duty ratio.

In summary, the operation of the rotation speed detection circuit 50 is as follows:

(1) when the dc motor 200 normally works, the driving current flowing through the dc motor 200 is smaller than the threshold current Im, the working voltage of the dc motor 200 sampled by the seventh resistor R7 is filtered by the eighth resistor R8 and the third capacitor C3 and then sent to the controller 10, the controller 10 performs difference calculation on the working voltage of the dc motor 200 sampled by the seventh resistor R7 and the preset voltage, and according to the result of the difference calculation, the duty ratio of the PWM signal output by the controller 10 is adjusted until the working voltage of the dc motor 200 sampled by the rotation speed detection circuit 50 reaches within the allowable deviation of the preset voltage, thereby achieving the purpose of speed regulation of the dc motor 200.

(2) When the dc motor 200 is abnormal, the driving current flowing through the dc motor 200 is greater than or equal to the threshold current Im, the working voltage of the dc motor 200 sampled by the seventh resistor R7 is filtered by the eighth resistor R8 and the third capacitor C3 and then sent to the controller 10, at this time, the working voltage is greater than or equal to the conduction voltage VB of the base of the NPN triode Q3, and the controller 10 controls the PWM signal to be at a low level, so as to achieve the purpose of software-controlled overcurrent protection, thereby further improving the safety of the dc motor control circuit 100.

The embodiment of the utility model provides a direct current motor control circuit, PWM signal through speed governing control circuit response controller transmission, produce drive power supply, drive power supply and the duty ratio direct proportional relation of PWM signal, H bridge drive circuit is according to drive power supply drive direct current motor work, drive power supply and direct current motor's rotational speed direct proportional relation, overcurrent protection circuit is when detecting the drive current of flowing through direct current motor more than or equal to threshold current, send protection signal to speed governing control circuit, make speed governing control circuit reduce drive power supply. Therefore, the embodiment of the utility model provides a convert PWM signal into drive power supply through speed governing control circuit to direct drive direct current motor, and when detecting the drive current of flowing through direct current motor when being more than or equal to threshold current through overcurrent protection circuit, make speed governing control circuit reduce drive power supply, in order to realize instant hardware protection, thereby promoted direct current motor control circuit's security and reliability.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit it; within the idea of the invention, also technical features in the above embodiments or in different embodiments can be combined, steps can be implemented in any order, and there are many other variations of the different aspects of the invention as described above, which are not provided in detail for the sake of brevity; although the present invention has been described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; such modifications and substitutions do not depart from the spirit and scope of the present invention.

Claims (10)

1. A dc motor control circuit, comprising:

a controller for transmitting a PWM signal;

the speed regulation control circuit is electrically connected with the controller and used for responding to the PWM signal and generating a driving power supply, and the driving power supply and the duty ratio of the PWM signal are in a direct proportion relation;

the H-bridge driving circuit is electrically connected with the speed regulation control circuit and used for driving the direct current motor to work according to the driving power supply, and the driving power supply is in direct proportion to the rotating speed of the direct current motor;

the overcurrent protection circuit is respectively electrically connected with the H-bridge drive circuit and the speed regulation control circuit and is used for sending a protection signal to the speed regulation control circuit when detecting that the drive current flowing through the direct current motor is greater than or equal to a threshold current, so that the speed regulation control circuit reduces the drive power supply; and the number of the first and second groups,

and the rotating speed detection circuit is respectively electrically connected with the H-bridge driving circuit and the controller and is used for sampling the working voltage of the direct current motor and sending the working voltage to the controller, so that the controller controls the speed regulation control circuit to regulate the driving power supply.

2. The dc motor control circuit of claim 1, wherein the speed regulation control circuit comprises:

a charging circuit;

and the starting circuit is respectively electrically connected with the controller and the charging circuit and used for controlling an external power supply to charge the charging circuit and provide the driving power supply for the H-bridge driving circuit when the PWM signal is at a high level, and controlling the external power supply to stop charging the charging circuit when the PWM signal is at a low level so that the charging circuit discharges to provide the driving power supply for the H-bridge driving circuit.

3. The dc motor control circuit of claim 2, wherein the start-up circuit comprises a first resistor, a second resistor, an NPN transistor, a third resistor, a fourth resistor, and a PNP transistor;

one end of the first resistor is used for receiving the PWM signal, and the other end of the first resistor is electrically connected with one end of the second resistor, the base electrode of the NPN triode and the overcurrent protection circuit; the other end of the second resistor is grounded; an emitting electrode of the NPN triode is grounded, and a collector electrode of the NPN triode is electrically connected with one end of the third resistor; the other end of the third resistor is electrically connected with one end of the fourth resistor and the base electrode of the PNP triode; the other end of the fourth resistor is electrically connected with an emitting electrode of the PNP triode and used for receiving an external power supply; and the collector electrode of the PNP triode is electrically connected with the charging circuit.

4. The dc motor control circuit of claim 3, wherein the charging circuit comprises an inductor and a first capacitor;

one end of the inductor is electrically connected with the collector of the PNP triode, and the other end of the inductor is electrically connected with the positive electrode of the first capacitor and used for outputting the driving power supply; and the negative electrode of the first capacitor is grounded.

5. The DC motor control circuit of claim 4, wherein the speed control circuit further comprises a free-wheeling circuit electrically connected between the start-up circuit and the charging circuit, for controlling the start-up circuit to stop charging the charging circuit when the external power supply stops charging the charging circuit when the PWM signal is at a low level, and performing free-wheeling processing on the back electromotive force generated by the charging circuit.

6. The dc motor control circuit of claim 5, wherein the freewheel circuit includes a first diode and a second diode;

the cathode of the first diode is electrically connected with the emitting electrode of the PNP triode, and the anode of the first diode is electrically connected with the collector electrode of the PNP triode, one end of the inductor and the cathode of the second diode; the anode of the second diode is grounded.

7. The direct current motor control circuit according to any one of claims 1 to 6, wherein the overcurrent protection circuit comprises:

the first sampling circuit is electrically connected with the H-bridge driving circuit and is used for sampling the driving current flowing through the direct current motor and generating sampling voltage;

and the switching circuit is respectively electrically connected with the first sampling circuit and the speed regulation control circuit and is used for biasing the PWM signal at a low level serving as the protection signal when the sampling voltage is greater than a voltage conduction threshold value, so that the speed regulation control circuit reduces the driving power supply.

8. The dc motor control circuit of claim 7, wherein the first sampling circuit comprises a fifth resistor, a second capacitor, and a sixth resistor;

one end of the fifth resistor is electrically connected with the H-bridge driving circuit, and the other end of the fifth resistor is electrically connected with one end of the second capacitor, one end of the sixth resistor and the switch circuit; the other end of the second capacitor is grounded; the other end of the sixth resistor is grounded.

9. The direct current motor control circuit according to any one of claims 1 to 6, wherein the rotation speed detection circuit includes a seventh resistor, an eighth resistor, and a third capacitor;

one end of the seventh resistor is electrically connected with the H-bridge driving circuit and one end of the eighth resistor, and the other end of the seventh resistor is grounded; the other end of the eighth resistor is electrically connected with one end of the third capacitor and the controller; the other end of the third capacitor is grounded.

10. A dc motor control system, comprising:

a direct current motor;

the dc motor control circuit of any of claims 1 to 9, electrically connected to the dc motor.

Images