Constant rotational speed control circuit for electric motor, electric motor control circuit for electric hair clipper, and electric hair clipper

Abstract

The present invention provides a constant rotational speed control circuit for an electric motor, an electric motor control circuit for an electric hair clipper, and an electric hair clipper. The constant rotational speed control circuit for an electric motor comprises: an electric motor driving circuit, an electric motor protection circuit, an electric motor rotational speed measurement circuit, an electric motor current measurement circuit and a master control unit, wherein the master control unit is electrically connected to the electric motor driving circuit and outputs a rotational speed control signal to a control end of the electric motor driving circuit; the electric motor driving circuit is electrically connected to a controlled electric motor, and regulates the rotational speed of the controlled electric motor on the basis of the rotational speed control signal; a signal input end of the electric motor rotational speed measurement circuit is electrically connected to the controlled electric motor, and a signal output end of the electric motor rotational speed measurement circuit is electrically connected to the master control unit; the electric motor current measurement circuit is connected in series to the controlled electric motor, and a signal output end of the electric motor current measurement circuit is electrically connected to the master control unit; and the electric motor protection circuit inputs an acquired electric motor voltage signal into the master control unit. The present invention solves the problem of it not being possible for an electric hair clipper to regulate the rotational speed on the basis of a load change, thereby improving the efficiency and effect of hair cutting.

Description

Motor constant speed control circuit, electric hair clipper motor control circuit, and electric hair clipper Technical Field

[0001] The present invention relates to the field of motor control, and in particular to a motor constant speed control circuit, an electric clipper motor control circuit, and an electric clipper. Background Art

[0002] Electric clippers are a common tool for haircutting and styling, and are one of the most common tools used by barbers. Traditional electric clippers generally consist of fixed teeth, movable teeth, an adjustable handle, a housing, and electrical components housed within the housing. They require electricity for operation. Common electric clippers on the market typically use either AC power directly to drive the motor or batteries to power the motor. Under constant voltage and load conditions, the motor maintains a stable speed. However, when the clippers encounter a large amount of hair, the motor speed decreases, resulting in unstable operation, which affects cutting force and can even cause hair to become trapped in the clippers, causing pain to the user. When fully charged, existing electric clippers rotate at high speed due to the high voltage, resulting in high blade temperatures and loud noise. When the battery charge remains below 20%, the voltage drops, causing the blade head to rotate too slowly and reduce cutting force, thus affecting the barber's work efficiency and the user's comfort.

[0003] In the Chinese patent document with publication number CN203863695U, a motor speed control device for electric hair clippers is disclosed, comprising a housing and a motor, a cutter head, and an eccentric device arranged inside the housing, wherein the eccentric device is fixed to the output shaft of the motor, and the cutter head is arranged at the top of the eccentric device. It also includes a bracket, a magnet, and a control board, wherein the bracket is fixed to the eccentric device, the magnet is fixed to the bracket, and a speed sensor for sensing the motor speed is provided below the magnet. The speed sensor is connected to the control board via a wire, and the control board has a processor IC. The control board also has a voltage output terminal, which is connected to the motor via a wire. However, the patent document lacks a motor protection circuit, which can easily cause damage to the motor when the motor load is too large.

[0004] Chinese patent publication CN101174810A discloses an electric hair clipper circuit comprising a motor, a motor drive circuit, a motor speed detection circuit, an MCU, a motor protection circuit, and a motor stall protection circuit. The motor detection circuit includes a speed collector that collects the motor's rotational speed. An output of the motor detection circuit is connected to an input of the MCU, an output of the MCU is connected to an input of the motor drive circuit, and an output of the motor drive circuit is connected to the motor.

[0005] Summary of the Invention

[0006] In view of the defects in the prior art, the purpose of the present invention is to provide a motor constant speed control circuit, an electric clipper motor control circuit and an electric clipper.

[0007] According to the present invention, a motor constant speed control circuit includes: a motor drive circuit, a motor protection circuit, a motor speed detection circuit, a motor current detection circuit and a main control unit;

[0008] The main control unit is electrically connected to the motor drive circuit and outputs a speed control signal to the control end of the motor drive circuit; the motor drive circuit is electrically connected to the controlled motor and adjusts the speed of the controlled motor according to the speed control signal; the signal input end of the motor speed detection circuit is electrically connected to the controlled motor, and the signal output end of the motor speed detection circuit is electrically connected to the main control unit; the motor current detection circuit is connected in series with the controlled motor, and the signal output end of the motor current detection circuit is electrically connected to the main control unit.

[0009] Preferably, the motor driving circuit includes a MOS transistor Q1, a source of the MOS transistor Q1 is connected to the motor driving voltage VBAT, a drain of the MOS transistor Q1 is connected to the positive electrode of the motor, and a gate of the MOS transistor Q1 is electrically connected to the main control unit.

[0010] Preferably, the motor protection circuit includes a diode D1 and a filter capacitor C3 connected in parallel with the positive and negative poles of the motor respectively.

[0011] Preferably, the motor protection circuit further includes a resistor R7 and a capacitor C4, one end of the resistor R7 is electrically connected to the positive pole of the motor, the other end of the resistor R7 is electrically connected to one end of the capacitor C4 and the main control unit, and the other end of the capacitor C4 is grounded.

[0012] Preferably, the motor current detection circuit includes a resistor R5, a resistor R6, a capacitor C5 and a capacitor C6 arranged in parallel, one end of the resistor R5 and the resistor R6 is electrically connected to the negative pole of the motor, and the other end of the resistor R5 and the resistor R6 is grounded, a resistor R8 is connected in series between the end of the capacitor C5 close to the negative pole of the motor and the end of the capacitor C6 close to the negative pole, and the end of the capacitor C6 close to the negative pole of the motor is connected to the main control unit.

[0013] Preferably, the motor speed detection circuit includes a transistor Q2, the base of the transistor Q2 is electrically connected to the speed signal output end of the motor, the collector of the transistor Q2 is electrically connected to the speed test voltage end VDD and the main control unit respectively, and the emitter of the transistor Q2 is grounded.

[0014] Preferably, the motor speed detection circuit further includes a diode D2, a resistor R3, a resistor R4, a resistor R9, and a capacitor C1 and a capacitor C2;

[0015] The positive electrode of the diode D2 is electrically connected to the speed signal output end of the controlled motor, the negative electrode of the diode D2 is electrically connected to one end of the resistor R4 and one end of the capacitor C1 respectively, the other end of the resistor R4 is electrically connected to the base of the transistor Q2 and one end of the capacitor C2 respectively, the other end of the capacitor C1, the other end of the capacitor C2 and the emitter of the transistor Q2 are connected and grounded; one end of the resistor R9 is electrically connected to the collector of the transistor Q2, and the other end of the resistor R9 is connected to the speed test voltage end VDD.

[0016] Preferably, the motor drive circuit further includes a resistor R1 and a resistor R2, wherein both ends of the resistor R1 are electrically connected to the motor drive voltage VBAT and the gate of the MOS tube Q1 respectively, and the resistor R2 is arranged in series between the gate of the MOS tube Q1 and the main control unit.

[0017] A control circuit for an electric clipper head motor provided by the present invention includes the above-mentioned motor constant speed control circuit.

[0018] An electric hair clipper provided by the present invention includes a motor, and the motor adopts the control circuit of the electric hair clipper head motor described above.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1. The present invention inputs the speed signal of the controlled motor into the main control unit through the motor speed detection circuit. The main control unit changes the voltage at both ends of the motor through the motor drive circuit, thereby controlling the speed of the motor. This solves the problem that the speed of the electric clippers decreases due to increased load, and the speed of the electric clippers cannot be adjusted according to the number of haircuts, thereby affecting the efficiency and effect of haircutting. At the same time, it also solves the problem that the speed of the electric clippers increases due to reduced load, which increases the noise of the electric clippers and causes the blade to heat up, thereby affecting the use effect.

[0021] 2. The resistor R7 and capacitor C4 in this circuit form an RC filter circuit, which inputs the filtered motor voltage signal into the main control unit to monitor the voltage across the motor in real time to prevent motor and circuit failures caused by abnormal voltage.

[0022] 3. Capacitor C5, resistor R8, and capacitor C6 in this circuit form a π-type signal filter circuit, which filters the collected signal before inputting it into the main control unit. Diode D2 in the motor speed detection circuit is used to filter out the motor's useless reverse speed signal, making the measurement more accurate.

[0023] 4. The motor constant speed control circuit provided by the present invention has a simple structure and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Other features, objects and advantages of the present invention will become more apparent upon reading the detailed description of non-limiting embodiments with reference to the following drawings:

[0025] FIG1 is a structural diagram of a motor constant speed control circuit in the present invention;

[0026] FIG2 is a schematic diagram of a motor current detection process in the present invention;

[0027] FIG3 is a schematic diagram of a motor speed detection process in the present invention. DETAILED DESCRIPTION

[0028] The present invention will be described in detail below with reference to specific embodiments. The following examples will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those skilled in the art, several changes and improvements can be made without departing from the scope of the present invention. These all fall within the scope of protection of the present invention.

[0029] The present invention provides a motor constant speed control circuit, as shown in FIG1 , comprising: a motor drive circuit, a motor protection circuit, a motor speed detection circuit, a motor current detection circuit, and a main control unit.

[0030] The main control unit is electrically connected to the motor drive circuit and outputs a speed control signal to the control end of the motor drive circuit; the motor drive circuit is electrically connected to the controlled motor and adjusts the speed of the controlled motor according to the speed control signal; the signal input end of the motor speed detection circuit is electrically connected to the controlled motor, the signal output end of the motor speed detection circuit is electrically connected to the main control unit, the motor current detection circuit is connected in series with the controlled motor, the signal output end of the motor current detection circuit is electrically connected to the main control unit, and the motor protection circuit inputs the collected motor voltage signal into the main control unit.

[0031] The motor speed detection circuit inputs the processed motor speed signal to the main control unit. The main control unit dynamically adjusts the output voltage of the motor drive circuit according to the difference between the actual speed and the expected speed, thereby changing the motor speed and keeping it consistent under different working conditions and loads.

[0032] Each circuit is described in further detail below.

[0033] The motor drive circuit includes a MOS transistor Q1, and also includes resistors R1 and R2. The source of the MOS transistor Q1 is connected to the motor drive voltage VBAT, the drain of the MOS transistor Q1 is connected to the positive electrode of the motor, and the gate of the MOS transistor Q1 is electrically connected to the main control unit. The two ends of the resistor R1 are electrically connected to the motor drive voltage VBAT and the gate of the MOS transistor Q1, respectively. The resistor R2 is arranged in series between the gate of the MOS transistor Q1 and the main control unit. The resistors R1 and R2 transmit a speed control signal from the main control unit to the MOS transistor Q1. The MOS transistor Q1 is used to control the on / off of the motor drive voltage VBAT to drive the motor.

[0034] The motor protection circuit includes a diode D1 and a filter capacitor C3 connected in parallel with the positive and negative poles of the motor, respectively, and also includes a resistor R7 and a capacitor C4. One end of the resistor R7 is electrically connected to the positive pole of the motor, and the other end of the resistor R7 is electrically connected to one end of the capacitor C4 and the main control unit. The other end of the capacitor C4 is grounded. The diode D1 is connected in parallel at both ends of the controlled motor to prevent the motor's reverse electromotive force from impacting the MOS tube Q1 and causing damage to the device. The filter capacitor C3 makes the voltage signal of the controlled motor more stable. The resistor R7 and capacitor C4 form an RC filter circuit. The output "VM" signal is the filtered motor voltage signal and is electrically connected to the main control unit. It monitors the voltage at both ends of the motor in real time to prevent voltage anomalies from causing motor and circuit failures.

[0035] The motor current detection circuit includes a resistor R5, a resistor R6, a capacitor C5 and a capacitor C6 arranged in parallel, one end of the resistor R5 and the resistor R6 is electrically connected to the negative pole of the motor, and the other end of the resistor R5 and the resistor R6 is grounded. A resistor R8 is connected in series between the end of the capacitor C5 close to the negative pole of the motor and the end of the capacitor C6 close to the negative pole, and the end of the capacitor C6 close to the negative pole of the motor is connected to the main control unit.

[0036] As shown in Figure 2, resistors R5 and R6 are sampling resistors used to collect motor current signals. Specifically, when the controlled motor is operating, current flows through this circuit, generating a voltage drop across the sampling resistors. The main control unit collects the voltage across the sampling resistors and calculates the current flowing through the motor by dividing the voltage difference between the two terminals by the resistance of the sampling resistors. If an overcurrent condition occurs, the circuit enters protection mode; otherwise, the circuit operates normally.

[0037] Capacitor C5, resistor R8 and capacitor C6 together form a π-type signal filtering circuit, which filters the collected motor current signal and outputs it to the main control unit.

[0038] The motor speed detection circuit includes a transistor Q2, a diode D2, a resistor R3, a resistor R4, a resistor R9, and capacitors C1 and C2. The base of the transistor Q2 is electrically connected to the speed signal output terminal of the motor, the collector of the transistor Q2 is electrically connected to the speed test voltage terminal VDD and the main control unit, and the emitter of the transistor Q2 is grounded. The anode of the diode D2 is electrically connected to the speed signal output terminal of the controlled motor, the cathode of the diode D2 is electrically connected to one end of the resistor R4 and one end of the capacitor C1, the other end of the resistor R4 is electrically connected to the base of the transistor Q2 and one end of the capacitor C2, the other end of the capacitor C1, the other end of the capacitor C2, and the emitter of the transistor Q2 are connected and grounded; one end of the resistor R9 is electrically connected to the collector of the transistor Q2, and the other end of the resistor R9 is electrically connected to the speed test voltage terminal VDD.

[0039] As shown in Figure 3, when the controlled motor rotates, the commutator emits a high-level signal when passing through the speed detection point. This signal is controlled by the circuit to turn on transistor Q2, thereby outputting a series of square waves. Transistor Q2 converts the motor speed signal into stable high and low-level signals and outputs them to the main control unit. The main control unit calculates the controlled motor speed by counting the square waves. Diode D2 filters out the motor's useless reverse speed signal. Resistors R3 and R4, and capacitors C1 and C2 form the signal filtering circuit. Resistor R9 acts as a signal pull-up resistor, providing a stable high-level signal.

[0040] The present invention also discloses a control circuit for a hair clipper head motor, including a motor constant speed control circuit, which can achieve constant speed regulation of the hair clipper. The present invention also provides an electric hair clipper, which includes a motor. The motor uses the control circuit of the hair clipper head motor to control the speed, thereby achieving intelligent control of constant speed under different loads, ensuring good hair cutting results.

[0041] The above describes specific embodiments of the present invention. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art may make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. The embodiments of this application and the features in the embodiments may be combined with each other in any manner unless there is a conflict.

Claims

1. A motor constant speed control circuit, characterized in that: include: Motor drive circuit, motor protection circuit, motor speed detection circuit, motor current detection circuit and main control unit; The main control unit is electrically connected to the motor drive circuit, and outputs a speed control signal to the control end of the motor drive circuit; the motor drive circuit is electrically connected to the controlled motor, and adjusts the speed of the controlled motor according to the speed control signal; the signal input end of the motor speed detection circuit is electrically connected to the controlled motor, and the signal output end of the motor speed detection circuit is electrically connected to the main control unit; the motor current detection circuit is connected in series with the controlled motor, and the signal output end of the motor current detection circuit is electrically connected to the main control unit; the motor protection circuit inputs the collected motor voltage signal into the main control unit.

2. The motor constant speed control circuit according to claim 1, characterized in that: The motor driving circuit comprises a MOS tube Q1, a source of the MOS tube Q1 is connected to a driving voltage VBAT of the motor, a drain of the MOS tube Q1 is connected to a positive electrode of the motor, and a gate of the MOS tube Q1 is electrically connected to a main control unit.

3. The motor constant speed control circuit according to claim 1, characterized in that: The motor protection circuit includes a diode D1 and a filter capacitor C3 which are respectively connected in parallel with the positive and negative poles of the motor.

4. The motor constant speed control circuit according to claim 3, characterized in that: The motor protection circuit also includes a resistor R7 and a capacitor C4, one end of the resistor R7 is electrically connected to the positive electrode of the motor, the other end of the resistor R7 is electrically connected to one end of the capacitor C4 and the main control unit, and the other end of the capacitor C4 is grounded.

5. The motor constant speed control circuit according to claim 1, characterized in that: The motor current detection circuit includes a resistor R5, a resistor R6, a capacitor C5 and a capacitor C6 arranged in parallel, one end of the resistor R5 and the resistor R6 are electrically connected to the negative pole of the motor, and the other end of the resistor R5 and the resistor R6 are grounded, a resistor R8 is connected in series between one end of the capacitor C5 close to the negative pole of the motor and one end of the capacitor C6 close to the negative pole, and one end of the capacitor C6 close to the negative pole of the motor is connected to the main control unit.

6. The motor constant speed control circuit according to claim 1, characterized in that: The motor speed detection circuit includes a transistor Q2, the base of the transistor Q2 is electrically connected to the speed signal output end of the motor, the collector of the transistor Q2 is electrically connected to the speed test voltage end VDD and the main control unit, and the emitter of the transistor Q2 is grounded.

7. The motor constant speed control circuit according to claim 6, characterized in that: The motor speed detection circuit also includes a diode D2, a resistor R3, a resistor R4, a resistor R9, and a capacitor C1 and a capacitor C2; The anode of the diode D2 is electrically connected to the speed signal output terminal of the controlled motor, the cathode of the diode D2 is electrically connected to one end of the resistor R4 and one end of the capacitor C1, and the other end of the resistor R4 is electrically connected to the transistor The base of Q2 is electrically connected to one end of the capacitor C2, the other end of the capacitor C1, the other end of the capacitor C2 and the emitter of the transistor Q2 are connected and grounded; one end of the resistor R9 is electrically connected to the collector of the transistor Q2, and the other end of the resistor R9 is connected to the speed test voltage terminal VDD.

8. The motor constant speed control circuit according to claim 1, characterized in that: The motor drive circuit further includes a resistor R1 and a resistor R2. The two ends of the resistor R1 are electrically connected to the motor drive voltage VBAT and the gate of the MOS tube Q1 respectively. The resistor R2 is arranged in series between the gate of the MOS tube Q1 and the main control unit.

9. A control circuit for a motor of an electric hair clipper head, characterized in that: The invention comprises a motor constant speed control circuit as described in any one of claims 1 to 8.

10. An electric hair clipper, characterized in that: It comprises a motor, and the motor adopts the control circuit of the electric clipper head motor according to claim 9.

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