Circuit for driving motor by PWM (Pulse Width Modulation) signal

Abstract

The utility model discloses a circuit for driving a motor by a PWM (Pulse Width Modulation) signal. The driving circuit comprises two parts which are connected, a PWM driving signal is input into a driving signal level conversion part and is transmitted to a motor push-pull driving part after level conversion, the motor push-pull driving part is connected to the two ends of a motor M, and the driving signal level conversion part comprises two triodes and a plurality of resistors. The motor push-pull driving part comprises two triodes, a plurality of resistors and MOS (Metal Oxide Semiconductor) tubes; and the PWM driving signal outputs a high-low change PWM signal, and when the high level and the low level of the PWM signal respectively and correspondingly open and close the MOS tube M1, the motor M1 is frequently charged and discharged. According to the invention, rapid charging opening and rapid discharging opening can be carried out on the motor driving MOS tube, so that the driving circuit can be ensured to carry out stable adjustment on the motor under the frequency of more than ten KHz; and the counter electromotive force of the motor is inhibited when the motor is subjected to PWM regulation, so that the service life of the driving MOS tube is prolonged.

Description

Technical Field

[0001] The utility model relates to the technical field of automobile electronic circuits, in particular to a circuit for driving a motor using a PWM signal. Background Art

[0002] PWM stands for pulse width modulation. PWM speed regulation, at a fixed frequency, adjusts the voltage across a DC motor by controlling the on and off times of the motor's MOSFET within a cycle, thereby regulating the motor's speed. PWM speed regulation offers advantages such as easy control, smooth speed regulation, and fast response, making it widely used in DC motor speed regulation.

[0003] If the motor is switched on and off with PWM, and the charging, discharging, and back-electromotive force suppression circuits of the motor-driven MOSFET are not properly designed, the product life will be affected. In some core chassis components, motor failure will affect driving safety. Utility Model Content

[0004] In order to solve the problems existing in the background technology, the utility model provides a circuit for driving a motor using a PWM signal.

[0005] The technical solution of the present utility model is achieved as follows:

[0006] The circuit of the utility model comprises two parts connected to each other: a driving signal level conversion part and a motor push-pull driving part; the PWM driving signal MCU_DRV input by an external signal generator is input into the driving signal level conversion part, and after level conversion, it is transmitted to the motor push-pull driving part to perform PWM drive control on the motor, and the motor push-pull driving part is connected to both ends of the motor M.

[0007] The drive signal level conversion part includes a transistor Q9, a transistor Q7, a resistor R8, a resistor R9, a resistor R11 and a resistor R12. The base of the transistor Q9 is connected to the PWM drive signal MCU_DRV via the resistor R11, the emitter is grounded, the emitter is connected to the base of the transistor Q7 via the resistor R12, the collector of the transistor Q9 is connected to the collector of the transistor Q7, and the base of the transistor Q7 is connected to its own emitter via the resistor R8 and the resistor R9 in sequence. At the same time, the collectors of the transistor Q9 and the transistor Q7 are both connected to the motor push-pull drive part.

[0008] The transistor Q7 is a PNP transistor, and the transistor Q9 is an NPN transistor.

[0009] The motor push-pull drive section includes a transistor Q8, a transistor Q10, a resistor R10, a resistor R13, and a MOS transistor M1. The bases of the transistors Q8 and Q10 are both connected to the collectors of the transistors Q9 and Q7 in the drive signal level conversion section. The collector of the transistor Q8 is connected to the collector of the transistor Q10. The emitter of the transistor Q10 is grounded. The collector of the transistor Q8 / the collector of the transistor Q10 is connected to the gate of the MOS transistor M1 via the resistor R10. The emitter of the transistor Q8 is connected to one end of the resistor R13. The other end of the resistor R13 is connected between the resistor R8 and the resistor R9 in the drive signal level conversion section. The other end of the resistor R13 is connected to one end of the motor M and is also connected to the power supply VBAT. The source of the MOS transistor M1 is grounded, and the drain is connected to the other end of the motor M.

[0010] The transistor Q8 is a PNP transistor, and the transistor Q10 is an NPN transistor.

[0011] The motor M1 is an inductive load, and a diode D1 is connected in parallel at both ends of the motor M.

[0012] The anode of the diode D1 is connected to the drain of pin 1 of the MOS tube M1, and the cathode is directly connected to the power supply VBAT.

[0013] Beneficial effects of the utility model:

[0014] This circuit can quickly charge and discharge the motor-driving MOSFET, ensuring the driver circuit can stably regulate the motor at frequencies exceeding 10 kHz. Freewheeling diodes are designed at both ends of the motor to suppress the motor's back EMF during PWM control, thereby extending the life of the driver MOSFET. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 The schematic diagram of a circuit for driving a motor using a PWM signal. DETAILED DESCRIPTION

[0016] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0017] like Figure 1 As shown, the circuit includes two parts connected to each other: a driving signal level conversion part 1 and a motor push-pull driving part 2; the PWM driving signal MCU_DRV input by the external signal generator is input to the driving signal level conversion part 1 and is transmitted to the motor push-pull driving part 2 after level conversion to perform PWM drive control on the motor. The motor push-pull driving part 2 is connected to both ends of the motor M.

[0018] The driving signal level conversion part 1 includes transistor Q9, transistor Q7, resistor R8, resistor R9, resistor R11 and resistor R12. The base of pin b of transistor Q9 is connected to the PWM driving signal MCU_DRV through resistor R11, the emitter of pin e is grounded, the emitter of pin e is connected to the base of pin b of transistor Q7 through resistor R12, the collector of pin c of transistor Q9 is connected to the collector of pin c of transistor Q7, and the base of pin b of transistor Q7 is connected to its own emitter of pin e through resistor R8 and resistor R9 in sequence. At the same time, the collectors of pin c of transistor Q9 and transistor Q7 are both connected to the base of pin b of transistor Q8 and the base of pin b of transistor Q10 in the motor push-pull driving part 2.

[0019] The motor push-pull drive part 2 includes transistor Q8, transistor Q10, resistor R10, resistor R13, MOS tube M1 and diode D1; the base of the transistor Q8 and the transistor Q10's pin b are connected to the collector of the transistor Q9 and the transistor Q7's pin c in the drive signal level conversion part 1, the collector of the transistor Q8's pin c is connected to the collector of the transistor Q10's pin c, the emitter of the transistor Q10's pin e is grounded, and the transistor Q8's pin c is connected to the ground. The collector of the collector / transistor Q10, pin c, is connected to the gate of pin 2 of the MOS tube M1 via resistor R10. The emitter of pin e of the transistor Q8 is connected to one end of a resistor R13. The other end of the resistor R13 is connected between resistors R8 and R9 of the drive signal level conversion part 1. The other end of the resistor R13 is connected to one end of the motor M and is also connected to the power supply VBAT. The source of pin 3 of the MOS tube M1 is grounded, and the drain of pin 1 is connected to the other end of the motor M.

[0020] In a specific implementation, the transistor Q7 is a PNP transistor, the transistor Q9 is an NPN transistor, the transistor Q8 is a PNP transistor, and the transistor Q10 is an NPN transistor.

[0021] The motor M1 is an inductive load, and a diode D1 is connected in parallel across the motor M. More specifically, the anode of the diode D1 is connected to the drain of pin 1 of the MOS tube M1, and the cathode is directly connected to the power supply VBAT.

[0022] In a specific implementation, the model of the MOS tube is IAUCN04SN005, the model of the transistors Q7 and Q8 are PNP tubes is Q2N2904, and the model of the transistors Q10 and Q9 are NPN tubes is Q2N2222.

[0023] The resistance value of resistor R9 is 2K, the resistance value of resistor R8 is 2K, the resistance value of resistor R12 is 10K, the resistance value of resistor R11 is 2K, the resistance value of resistor R10 is 20R, the resistance value of resistor R13 is 2K, and the model of diode D1 is: STPS3045CGY-TR.

[0024] like Figure 1 As shown, the specific implementation process of the utility model is as follows:

[0025] The main functions of the circuit include three parts: driving the motor to charge and turn on, driving the motor to discharge and turn off, and suppressing the motor's back electromotive force.

[0026] 1. Drive motor charging is turned on

[0027] In the drive signal level conversion part 1, the PWM drive signal MCU_DRV outputs a high potential, and the voltage difference between the base of pin b and the emitter of pin e of transistor Q9 is greater than 0.7V, so that transistor Q9 is turned on, and the collector of pin c of transistor Q9 is connected to the emitter of pin e, that is, the potential of the collector of pin c is 0V.

[0028] In the motor push-pull drive section 2, the emitter of transistor Q8's pin e is connected to the power supply VBAT (+12V) via resistor R13. Since the base of transistor Q8's pin b is connected to the collector of transistor Q9's pin c, it is at 0V. At this time, the voltage difference between transistor Q8's pin e emitter and pin b base is greater than 0.7V, causing transistor Q8 to conduct. Meanwhile, transistor Q10's pin b base and pin e emitter are both at ground voltage, with a voltage difference of 0V between them. Therefore, transistor Q10 is off and does not conduct.

[0029] The power supply end of the motor M is always connected to the power supply VBAT. The MOS tube M1 is driven to start the charging path: the voltage of the power supply VBAT is transmitted to the gate of the MOS tube M1 through the resistor R13, the transistor Q8, and the resistor R10 in sequence, that is, VBAT-R13-Q8-R10-M1 gate. At this time, the voltage difference between the gate of the MOS tube M1 and the source of the pin 3 is almost VBAT, meeting the turn-on condition voltage difference of 3V, making the MOS tube M1 conductive, the ground terminal of the motor M is grounded, and the motor starts.

[0030] The triode Q7 conducts periodically. Initially, the e pin of the triode Q7 comes from VBAT through the resistor R9, and the potential of the transmitter b comes from the voltage division of the resistors R8 and R9 of VBAT. Therefore, the potential of the e>b pin causes the triode Q7 to conduct. At this time, the potential of the e of the triode Q7 is the same as that of its c. And because the triode Q9 conducts and its c potential is 0V, the e of the triode Q7 is 0V. At this time, the e<b of the triode Q7 will be disconnected until the voltage at the e end of the triode Q7 is greater than the voltage at the b end. Then it will conduct again and repeat the above process. Here, there is no need to care whether the triode Q7 conducts, because the only thing affecting the subsequent motor push-pull drive part is the potential of the c pin of the triode Q9, and it is always 0V and is not affected by the triode Q7.

[0031] 2. Drive the motor to discharge and shut down

[0032] In the drive signal level conversion part 1, the PWM drive signal MCU_DRV outputs a low potential, and the voltage difference between the base of the b pin and the emitter of the e pin of the triode Q9 is less than 0.7V, causing the triode Q9 port not to conduct. The collector of the c pin of the triode Q9 is connected to the emitter of the e pin, that is, the potential of the c pin of the collector is 0V.

[0033] At this time, for the triode Q7, the potential of the base of the b pin of the triode Q7 is:

[0034] VBAT*(R12 / (R12+R8)) = 12*(10K / (2K+10K)) = 10V

[0035] The potential of the base of the b pin of the triode Q7 is almost VBAT (+12V), meeting the condition that the voltage difference between the emitter of the e pin and the base of the b pin is greater than 0.7V, causing the triode Q7 to conduct. The voltage of the power supply VBAT is loaded onto the collector of the c pin of the triode Q7 through the resistor R9.

[0036] In the motor push-pull drive part 2, the potential of the collector of the c pin of the triode Q7 is respectively transmitted to the bases of the b pins of the triode Q8 and the triode Q10.

[0037] Since the emitter of the e pin of the triode Q8 is always connected to the power supply VBAT through the resistor R13, the voltage between the emitter of the e pin and the base of the b pin of the triode Q8 is almost equal, so the triode Q8 is disconnected.

[0038] For the triode Q10, the emitter of the e-pin of the triode Q10 itself is always grounded, and the voltage difference between the emitter of the e-pin and the base of the b-pin of the triode Q10 is greater than 0.7V, so the triode Q10 is turned on, and the potentials of the emitter of the e-pin and the collector of the c-pin of the triode Q10 itself are both 0V, which are the voltages of the grounded.

[0039] Drive motor discharge path of the MOS transistor: The gate of the MOS transistor M1 is grounded successively through the resistor R10 and the triode Q10, that is, the gate of the MOS transistor M1 - resistor R10 - Q10 - ground 0V, so that the gate voltage of the 2-pin of the MOS transistor M1 can quickly drop to 0V, so as to quickly turn off the MOS transistor M1, making the ground terminal of the motor M unable to be grounded and stopping the operation of the motor M.

[0040] 3. Suppress the back electromotive force of the motor

[0041] The motor M1 is an inductive load, and the PWM drive signal MCU_DRV outputs a PWM signal with high and low levels. During the PWM regulation process, the MOS transistor M1 will be frequently turned on and off according to the above mode.

[0042] When the motor M1 is turned off instantaneously from being turned on, due to the inductive load, its current cannot change suddenly, which will cause the voltage of the ground terminal of the 2-terminal of the motor M to be greater than the voltage of the power supply terminal of the 1-terminal, forming a positive high voltage. Since the voltage difference VDS between the drain and the source of the MOS transistor M1 is at most 40V, there is a probability of breakdown, resulting in damage to the MOS transistor.

[0043] When a high voltage exists at the 2-terminal of the motor M1 by designing the diode D1 at both ends of the motor, the present invention can utilize the forward conduction of the diode to discharge the energy to the power supply VBAT terminal, clamping the voltage of the diode D1 at VBAT + 0.7V < VDS = 40V, thereby ensuring and greatly improving the service life of the MOS transistor M1 when it is driven by the PWM signal.

[0044] Through the above operations, the motor can stably perform PWM regulation actions according to the PWM input of the drive signal.

Claims

1. A circuit for driving a motor using a PWM signal, characterized in that: The invention comprises two parts, a driving signal level conversion part (1) and a motor push-pull driving part (2), which are connected to each other; the PWM driving signal MCU_DRV inputted by the external signal generator is inputted into the driving signal level conversion part (1), and after level conversion, is transmitted to the motor push-pull driving part (2) to perform PWM driving control on the motor, and the motor push-pull driving part (2) is connected to both ends of the motor M.

2. The circuit for driving a motor using a PWM signal according to claim 1, wherein: The driving signal level conversion part (1) includes a transistor Q9, a transistor Q7, a resistor R8, a resistor R9, a resistor R11 and a resistor R12. The base of the transistor Q9 is connected to the PWM driving signal MCU_DRV via the resistor R11, the emitter is grounded, the emitter is connected to the base of the transistor Q7 via the resistor R12, the collector of the transistor Q9 is connected to the collector of the transistor Q7, the base of the transistor Q7 is connected to its own emitter via the resistor R8 and the resistor R9 in sequence, and the collectors of the transistor Q9 and the transistor Q7 are both connected to the motor push-pull driving part (2).

3. The circuit for driving a motor using a PWM signal according to claim 2, wherein: The transistor Q7 is a PNP transistor, and the transistor Q9 is an NPN transistor.

4. The circuit for driving a motor using a PWM signal according to claim 1, wherein: The motor push-pull drive part (2) includes a transistor Q8, a transistor Q10, a resistor R10, a resistor R13, and a MOS tube M1; the bases of the transistors Q8 and Q10 are both connected to the collectors of the transistors Q9 and Q7 in the drive signal level conversion part (1), the collector of the transistor Q8 is connected to the collector of the transistor Q10, the emitter of the transistor Q10 is grounded, and the collector of the transistor Q8 / the collector of the transistor Q10 is connected via the resistor R10 and the gate of the MOS tube M1, the emitter of the transistor Q8 is connected to one end of the resistor R13, the other end of the resistor R13 is connected between the resistor R8 and the resistor R9 of the drive signal level conversion part (1), the other end of the resistor R13 is connected to one end of the motor M and is also connected to the power supply VBAT, the source of the MOS tube M1 is grounded, and the drain is connected to the other end of the motor M.

5. The circuit for driving a motor using a PWM signal according to claim 4, wherein: The transistor Q8 is a PNP transistor, and the transistor Q10 is an NPN transistor.

6. The circuit for driving a motor using a PWM signal according to claim 1, wherein: The motor M is an inductive load, and a diode D1 is connected in parallel at both ends of the motor M.

7. The circuit for driving a motor using a PWM signal according to claim 6, wherein: The anode of the diode D1 is connected to the drain of pin 1 of the MOS tube M1, and the cathode is directly connected to the power supply VBAT.

Images