CN210075117U

CN210075117U - Speed regulator for DC motor

Info

Publication number: CN210075117U
Application number: CN201920379263.6U
Authority: CN
Inventors: 顾能华; 王海伦; 韩雪龙; 黄剑; 徐荣伟; 朱莉; 叶骏; 陈勇
Original assignee: Quzhou University
Current assignee: Quzhou University
Priority date: 2019-03-25
Filing date: 2019-03-25
Publication date: 2020-02-14
Anticipated expiration: 2029-03-25

Abstract

The utility model discloses a DC motor speed adjusting device belongs to motor speed governing technical field, including drive circuit, drive circuit includes optoelectronic coupler, power MOSFET, speed governing unit and MOS pipe, and optoelectronic coupler is arranged in DC motor H bridge drive circuit on for the produced interference of both sides ground potential difference has been suppressed, and power MOSFET is drive circuit's switching power supply, and the speed governing unit is arranged in drive circuit regulating voltage, and the MOS pipe is arranged in drive circuit and drives drive circuit. The utility model discloses two sets of PWM signals can not export simultaneously through program control, constitute the circuit by the opto-coupler and guaranteed four disconnection simultaneously under the control of singlechip, avoided the appearance of the phenomenon of switching on altogether, constitute the circuit by the opto-coupler simultaneously and also avoided receiving the problem of the interference of electromagnetic interference and ground potential difference easily to the quality of DC motor's speed governing has been improved, its travelling comfort is improved.

Description

Speed regulator for DC motor

Technical Field

The utility model relates to a motor speed adjusting device especially relates to a direct current motor speed adjusting device, belongs to motor speed control technical field.

Background

The motor is developed and perfected for many years, the technology is mature, the motor on the market is various in forms, but the motor has advantages and disadvantages, the direct current motor is good in stability, low in noise and low in power supply voltage, generally supplies power for safe extra-low voltage, is high in safety, can prevent safety hazards caused by electric shock and leakage to the greatest extent, is moderate in price and long in service life, and is beneficial to control cost and daily maintenance in production.

At present, a driving circuit of a direct current motor is easily interfered by electromagnetic interference and ground potential difference, and the speed regulation of the direct current motor in the current driving circuit is not ideal.

SUMMERY OF THE UTILITY MODEL

The utility model mainly aims to provide a DC motor speed adjusting device.

The purpose of the utility model can be achieved by adopting the following technical scheme:

the utility model provides a direct current motor speed adjusting device, includes drive circuit, drive circuit includes optoelectronic coupler, power MOSFET, speed adjusting unit and MOS pipe, optoelectronic coupler is used for direct current motor H bridge drive circuit for the produced interference of suppression both sides ground potential difference, power MOSFET is drive circuit's switching power supply, the speed adjusting unit is arranged in drive circuit adjusts voltage, the MOS pipe is arranged in drive circuit is used for driving drive circuit.

Preferably, the photoelectric coupler adopts a diode-diode photoelectric coupler or/and a diode-triode photoelectric coupler.

Preferably, the power MOSFET includes three pole contacts, the three pole contacts are a gate G contact, a source S contact and a drain D contact, respectively, and a group of diodes is connected in parallel between the drain D contact and the source S contact.

Preferably, the commercial power 220V ac power supply is stabilized by the power adapter to be a constant dc voltage, and is connected to the driving circuit.

Preferably, the MOS tube is a high-power MOS tube.

Preferably, the driving circuit is a variable voltage speed regulation dc motor.

The utility model has the advantages of: two sets of PWM signals can not be output simultaneously through program control, four simultaneous disconnections are guaranteed by the optical coupler forming circuit under the control of the single chip microcomputer, the appearance of common-mode conduction is avoided, and meanwhile, the problem that the circuit is easily interfered by electromagnetic interference and ground potential difference is solved by the optical coupler forming circuit, so that the quality of speed regulation of the direct current motor is improved, and the comfort of the direct current motor is improved.

Drawings

Fig. 1 is a diagram of a dc motor driving circuit according to a preferred embodiment of a dc motor speed adjusting apparatus according to the present invention;

fig. 2 is a circuit diagram of a diode-diode photocoupler of a preferred embodiment of a dc motor speed regulating device in accordance with the present invention;

fig. 3 is a circuit diagram of a diode-triode photocoupler of a preferred embodiment of a dc motor speed regulating device in accordance with the present invention;

fig. 4 is a dc pulse width speed control circuit diagram of a preferred embodiment of a dc motor speed control device according to the present invention;

fig. 5 is a graph of motor electrical drive voltage waveforms for a preferred embodiment of a dc motor speed adjustment device according to the present invention;

fig. 6 is a swing amplitude feedback circuit diagram of a preferred embodiment of a dc motor speed regulation device according to the present invention;

fig. 7 is a flow chart of a dc motor speed regulation procedure of a preferred embodiment of a dc motor speed regulation device according to the present invention;

fig. 8 is a diagram of a dc motor speed regulation system according to a preferred embodiment of a dc motor speed regulation device in accordance with the present invention;

FIG. 9 is a schematic circuit diagram of a prior art waverider;

fig. 10 is a diagram of a rectangular wave generated by a waverider in the prior art.

Detailed Description

In order to make the technical solutions of the present invention clearer and clearer for those skilled in the art, the present invention will be described in further detail with reference to the following embodiments and the accompanying drawings, but the embodiments of the present invention are not limited thereto.

In the prior art, a relation formula of a rotating speed V of a direct current motor and various parameters is as follows:

in the above formula, U-is the voltage across the armature circuit; r-total resistance of motor armature circuit; phi-motor flux; c_e-an electromotive constant; c_T-a torque constant; t-motor electromagnetic torque.

From the above formula, changing any one parameter of the resistance R of the armature circuit, the armature supply voltage U or the main flux Φ can adjust the rotation speed of the motor, so the speed adjusting method of the dc motor includes the following steps:

1. changing the resistance R of the armature circuit;

2. changing the armature supply voltage U;

3. the main flux phi is changed.

In the application, the driving circuit is used for regulating the speed of the direct current motor by variable voltage speed regulation, and the high-power MOS tube is used for driving, so that stepless smooth speed regulation can be performed within a certain range.

The mechanical characteristic equation of variable-pressure speed regulation is as follows:

in the equation, U_r-a rectified voltage; r_r-a rectifying means internal resistance.

From this equation, a set of parallel characteristics can be obtained when the rectified voltage is changed.

When the load torque is constant, Δ V is constant, which becomes the following equation:

in the prior art PWM method, as shown in fig. 9 and 10, when the switch is on, the power source E is applied to the dc motor, and when the switch is off, the dc power source is disconnected from the dc motor, the motor freewheels through the diode D, the voltage across the dc motor is approximately zero, and the cycle is repeated, and the voltage waveform across the dc motor is a rectangular wave.

The average voltage formula obtained by applying rectangular wave voltage to two ends of a direct current motor is as follows:

in the average voltage formula, T-the switching period of the switching element; t is t_on-the on-time of the switching element; delta-T_on-a switching duty cycle.

The direct current power supply is obtained by connecting a 220V alternating current power supply through a mains supply, a constant direct current voltage is obtained through voltage stabilization of a power adapter, and the constant direct current voltage is connected with a driving circuit, so that the direct current power supply is obtained.

In this embodiment, as shown in fig. 4 and 5, in the variable voltage speed regulation, the present application adopts a PWM method, i.e., pulse width modulation, to regulate the dc power supply, and VT1 to VT4 are four high-power transistors, and operate in a switching state, where bases of a pair of transistors on a diagonal line are simultaneously turned on or off by receiving the same control signal. If VT1 and VT4 are conducted, a positive voltage is applied to the armature of the motor; if VT2 and VT3 are turned on, a reverse voltage is applied to the motor armature. When they are alternately switched on at a high frequency (typically 2000Hz) and due to the effect of mechanical inertia, the motor turns and the speed of rotation are determined solely by the average value of this voltage.

Let the period of the rectangular wave be T and let the forward pulse width be T₁The average voltage formula is derived as follows:

from this equation, when T is constant, the duty ratio γ is changed by artificially changing the width of the positive pulse, and the Uav can be changed to achieve the purpose of speed regulation. When gamma is 0.5, Uav is 0, and the rotating speed of the motor is zero; when gamma is more than 0.5, when Uav is positive, the motor rotates forwards, and when gamma is 1, Uav is Us, and the forward rotating speed is highest; when gamma is less than 0.5, Uav is negative, the motor is reversely rotated, and when gamma is 0, Uav is-Us, the reverse rotation speed is highest, and the pulse width is continuously changed, so that the stepless speed regulation of the direct current motor can be realized.

In the embodiment of the present application, as shown in fig. 2 and fig. 3, the photocoupler adopts a diode-diode photocoupler or/and a diode-triode photocoupler, D1 is a light emitting diode, T2 is a phototriode, D1 and D2 or D1 and T2 are electrically insulated, after D1 passes through a current IF, the side of D1 emits infrared light, and D2 or T2 generates a current IC after being excited by light, so as to generate a voltage drop Vo on RL, thus converting the current IF into a current IC or a voltage Vo.

Therefore, IC or VO is only related to IF and is not related to the potential at both sides of the photoelectric coupler, thereby suppressing the interference generated by the ground potential difference at both sides.

In the embodiment of the present application, as shown in fig. 1, a power MOSFET is used as a switching power supply of a driving circuit, the power MOSFET includes three pole contacts, the three pole contacts are a gate G contact, a source S contact and a drain D contact, respectively, and a group of diodes is connected in parallel between the drain D contact and the source S contact.

In the embodiment of the present application, as shown in fig. 6 to 8, a rotary encoder composed of PT2559B is selected as a sensing circuit used in the swing feedback circuit of the feedback swing mechanism, and the PT2559B is a high-speed infrared photosensor and has two-way photosensitive sensing elements and two-way digital signal output.

In the control mainboard circuit, two groups of light control signals of PT2559B are connected to IO of a single chip microcomputer, a closed loop regulation and control loop is formed by a swing amplitude feedback module, the single chip microcomputer, a driving module, a direct current motor and a swing mechanism, the single chip microcomputer can judge the rotation direction of the swing mechanism according to the phase difference of output signals A, B phases of a PT2559B rotary encoder in the swing amplitude feedback module, the swing amplitude of the swing mechanism can be calculated by calculating the number of pulses of one path of signal A, and therefore the single chip microcomputer can control the driving module according to the swing direction and the swing amplitude of the swing mechanism in the process of controlling the swing mechanism, so that the corresponding regulation and control of the rotation direction, the force and the running time of the direct current motor are carried out, and the swing mechanism is driven.

The swing mechanism referred to herein is any mechanical structure having a swing function, such as a cradle or the like.

As shown in fig. 1 to 8, the operation process of the speed regulating device of the dc motor provided by this embodiment is as follows:

step 1: signals of the PWM0 and the PWM1 are generated by the programming of the single chip microcomputer, and two groups of PWM signals cannot be output simultaneously through program control;

step 2: the circuit formed by the optocouplers ensures that four switches are simultaneously switched off under the control of the singlechip, so that the common-mode conduction phenomenon is avoided;

and step 3: when one group of PWM pins are output, the corresponding pulse signals are connected to an optocoupler of an H-bridge circuit, and the two ends of a diode of the optocoupler are conducted by bearing a voltage with the forward direction larger than 0.7V, the corresponding phototriodes are conducted by the emitted light, and the working states of the power amplifying tubes IRF540 and IRF9540 can be controlled by whether the phototriodes are conducted or not;

and 4, step 4: the resistors in the H-bridge circuit have the functions of current limiting and voltage dividing, wherein the 390 omega resistor on the weak current signal side plays the role of current limiting after the diode is conducted, the resistor on the +24V side plays the role of voltage dividing, and the power amplifier tube can be conducted after the voltage dividing.

In summary, in this embodiment, the signals of the PWM0 and PWM1 are generated by programming of the single chip, two sets of PWM signals cannot be output simultaneously through program control, the circuit composed of the optocouplers ensures that four PWM pins are simultaneously turned off under the control of the single chip, thereby avoiding the occurrence of the common mode conduction phenomenon, when one set of PWM pins is output, the corresponding pulse signals are connected to the optocouplers of the H-bridge circuit, the two ends of the diode of the optocoupler are conducted by bearing a voltage of which the forward direction is greater than 0.7V, the light emitted by the optocouplers conducts the corresponding phototriodes, and whether the phototriodes are conducted or not can control the working states of the power amplification tubes IRF540 and IRF9540, the resistors in the H-bridge circuit have the current limiting and voltage dividing functions, wherein the 390 Ω resistor on the weak current signal side plays the current limiting role after the diode is conducted, the resistor on the +24V side plays the.

The above description is only a further embodiment of the present invention, but the scope of protection of the present invention is not limited thereto, and any person skilled in the art can replace or change the technical solution and the concept of the present invention within the scope of the present invention.

Claims

1. A speed regulating device of a direct current motor comprises a driving circuit, and is characterized in that: the driving circuit comprises a photoelectric coupler, a power MOSFET, a speed regulating unit and an MOS (metal oxide semiconductor) tube, wherein the photoelectric coupler is used on an H-bridge driving circuit of the direct-current motor and used for inhibiting interference generated by ground potential difference on two sides, the power MOSFET is a switching power supply of the driving circuit, the speed regulating unit is used for regulating voltage in the driving circuit, and the MOS tube is used for driving the driving circuit in the driving circuit.

2. A dc motor speed regulating device according to claim 1, wherein: the photoelectric coupler adopts a diode-diode photoelectric coupler or/and a diode-triode photoelectric coupler.

3. A dc motor speed regulating device according to claim 1, wherein: the power MOSFET comprises three pole contacts, wherein the three pole contacts are a grid G contact, a source S contact and a drain D contact respectively, and a group of diodes are connected in parallel between the drain D contact and the source S contact.

4. A dc motor speed regulating device according to claim 1, wherein: the commercial power 220V alternating current power supply is converted into constant direct current voltage through the voltage stabilization of the power adapter and is connected with the driving circuit.

5. A dc motor speed regulating device according to claim 1, wherein: the MOS tube is a high-power MOS tube.

6. A dc motor speed regulating device according to claim 1, wherein: the driving circuit is used for regulating the speed of the direct current motor by variable voltage speed regulation.