Transistor control circuit, direct current motor drive circuit and air conditioner

Abstract

The utility model provides a transistor control circuit, a DC motor drive circuit and an air conditioner, the transistor control circuit is applied to a DC motor and comprises a transistor and a transistor control unit, a parasitic capacitor is arranged between a grid electrode and a drain electrode of the transistor, and the transistor control unit is connected with the transistor. The transistor control unit comprises a correction capacitor, the correction capacitor is connected between the grid electrode and the source electrode of the transistor in parallel, and when the transistor is conducted, the correction capacitor is used for providing current for the stray capacitor. The correction capacitor is connected in parallel between the grid electrode and the source electrode of the transistor, the correction capacitor provides current for the stray capacitor, the influence of the stray capacitor in the transistor can be reduced, the phenomenon that the transistor is turned off by mistake is prevented, and therefore accurate control and energy efficiency utilization of the direct current motor are ensured.

Description

Technical Field

[0001] The utility model relates to the technical field of air conditioners, in particular to a transistor control circuit, a DC motor drive circuit and an air conditioner. Background Art

[0002] Modern air conditioning systems play a key role in providing indoor temperature and comfort control, of which DC motor speed drive circuits are an indispensable component. These circuits are often used to drive key components in air conditioning systems, such as fan motors, compressors, etc., and require precise control and efficient performance to ensure the overall performance and efficiency of the system. However, existing motor speed drive circuits have problems with poor waveform quality, which limits the efficiency and accuracy of the motor. These problems are usually caused by the Miller plateau effect of MOSFET (metal oxide semiconductor field effect transistor, i.e. MOS tube).

[0003] In the current motor speed control drive circuit, the Miller platform is caused by the voltage amplification effect between the input capacitor and the feedback capacitor of the MOSFET, resulting in a feedback capacitor due to the potential difference, called the Miller capacitor. When the input signal frequency of the MOSFET is high (for example, >20kHz), this capacitor will significantly affect the switching speed of the MOSFET, causing a delay time, namely the Miller platform time. This problem will affect the waveform of the air conditioner DC motor speed control drive circuit. Utility Model Content

[0004] The utility model solves the problem that the Miller capacitor affects the waveform of the speed regulating driving circuit of the air conditioner DC motor.

[0005] In order to solve the above problems, the utility model provides a transistor control circuit, which is applied to a DC motor. The transistor control circuit includes:

[0006] A transistor, wherein a parasitic capacitor is provided between a gate and a drain of the transistor;

[0007] A transistor control unit, the transistor control unit is connected to the transistor, the transistor control unit includes a correction capacitor, the correction capacitor is connected in parallel between the gate and source of the transistor, when the transistor is turned on, the correction capacitor is used to provide current for the parasitic capacitor.

[0008] The present application reduces the influence of the parasitic capacitance in the transistor by connecting a correction capacitor in parallel between the gate and source of the transistor and providing current to the parasitic capacitance through the correction capacitor, thereby preventing the transistor from being shut down by mistake, thereby ensuring the precise control and energy efficiency of the DC motor.

[0009] Optionally, the transistor control unit also includes an optocoupler and a driving resistor, the sixth pin of the optocoupler is connected to the gate of the transistor, the fifth pin of the optocoupler is connected to the source of the transistor, one end of the driving resistor is connected to the sixth pin of the optocoupler, and the other end of the driving resistor is connected to the correction capacitor.

[0010] Optionally, the transistor control unit also includes an optocoupler and a driving resistor, the sixth pin of the optocoupler is connected to one end of the driving resistor, the other end of the driving resistor is connected to the gate of the transistor, the fifth pin of the optocoupler is connected to a negative voltage, and the source of the transistor is grounded.

[0011] By applying a negative voltage power supply to the output end of the optocoupler, while the source end of the driving transistor is still connected to the power ground, the voltage at the highest point of the Miller platform is guaranteed to be lower than the transistor turn-on voltage, thereby preventing the transistor from being turned on by mistake.

[0012] Optionally, the eighth pin of the optocoupler is connected to a positive voltage, and a first capacitor is provided between the eighth pin of the optocoupler and the fifth pin of the optocoupler.

[0013] The first capacitor is provided to filter the signal so as to improve the stability of the circuit.

[0014] Optionally, the capacitance of the correction capacitor is greater than or equal to 0.01uf.

[0015] Optionally, the transistor control unit includes an optocoupler, a driving resistor and a diode, the sixth pin of the optocoupler is connected to the gate of the transistor, the fifth pin of the optocoupler is connected to the source of the transistor, one end of the driving resistor is connected to the sixth pin of the optocoupler, the other end of the driving resistor is connected to the gate of the transistor, the anode of the diode is connected to the gate of the transistor, and the cathode of the diode is connected to the sixth pin of the optocoupler.

[0016] Based on the optimization of the rising edge of the driving wave, the present application further connects a diode in anti-parallel to both ends of the driving resistor, so that the parasitic capacitance voltage at both ends of the transistor gate and source is quickly discharged through the diode, and the transistor is quickly turned off, thereby reducing the influence of the parasitic capacitance in the transistor.

[0017] The embodiment of the present application further provides a transistor control circuit, which is applied to a DC motor. The transistor control circuit includes:

[0018] A transistor, wherein a parasitic capacitor is provided between a gate and a drain of the transistor;

[0019] A transistor control unit, wherein the transistor control unit is connected to the transistor, and the transistor control unit includes an optocoupler, a driving resistor and a diode, wherein the sixth pin of the optocoupler is connected to the gate of the transistor, the fifth pin of the optocoupler is connected to the source of the transistor, one end of the driving resistor is connected to the sixth pin of the optocoupler, the other end of the driving resistor is connected to the gate of the transistor, the positive electrode of the diode is connected to the gate of the transistor, and the negative electrode of the diode is connected to the sixth pin of the optocoupler.

[0020] By connecting a diode in anti-parallel at both ends of the driving resistor, the parasitic capacitance voltage at both ends of the transistor gate and source can be quickly discharged through the diode, and the transistor can be quickly turned off.

[0021] The embodiment of the present application further provides a DC motor drive circuit, the DC motor drive circuit comprising:

[0022] DC motor coil;

[0023] Two transistor control circuits as described in any one of the above items, both of which are connected to the DC motor coil.

[0024] An embodiment of the present application further provides an air conditioner, which includes the DC motor drive circuit described above. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A first circuit diagram of a transistor control circuit provided in an embodiment of the present application;

[0026] Figure 2 A second circuit diagram of a transistor control circuit provided in an embodiment of the present application;

[0027] Figure 3 A third circuit diagram of the transistor control circuit provided in an embodiment of the present application;

[0028] Figure 4 A circuit diagram of a DC motor drive circuit provided in an embodiment of the present application.

[0029] Description of reference numerals:

[0030] Q1, transistor; U1, optocoupler; C3, first capacitor; R3, driving resistor; C4, correction capacitor; R4, second resistor; R1, first resistor; D5, diode; L, DC motor coil. DETAILED DESCRIPTION

[0031] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention will be described in detail below.

[0032] In the current motor speed control drive circuit, the Miller platform effect has the following effects on the waveform of the air conditioner DC motor speed control drive circuit:

[0033] 1. Reduced efficiency and energy efficiency: Unstable motor waveforms can cause the motor to consume excessive energy when driven at high frequencies, reducing the overall efficiency of the system and leading to unnecessary energy waste.

[0034] 2. Increased noise: Unstable motor drive waveforms will cause the motor to generate unnecessary noise and vibration, which in turn affects the comfort of the indoor environment and user experience.

[0035] 3. Shortened equipment life: Air-conditioning systems usually need to run for a long time, and the reliability of the equipment is crucial. Unstable motor drive waveforms may cause unnecessary stress on the motor and related components, which may increase the switching loss of power devices and shorten the life of the equipment.

[0036] 4. Reduced system stability: Unstable motor waveforms can cause the system to exhibit unstable responses under different conditions, thereby affecting the control of temperature and humidity and reducing system stability.

[0037] 5. Not in line with sustainable development goals: Under the trend of dual carbon and sustainable development, the waste of electricity is not only detrimental to users, but also has a negative impact on the environment, which is not in line with sustainable development goals.

[0038] Therefore, the present application provides a transistor control circuit, a DC motor drive circuit and an air conditioner to solve the above problems.

[0039] Among them, the transistor control circuit provided in the present application is applied to a DC motor, and the transistor control circuit includes a transistor Q1 and a transistor control unit, and a parasitic capacitor is arranged between the gate and the drain of the transistor Q1; the transistor control unit is connected to the transistor Q1, and the present application adjusts the rising edge of the driving waveform at both ends of the transistor Q1, adjusts the falling edge of the driving waveform at both ends of the transistor Q1, or adjusts the rising edge and the falling edge of the driving waveform at both ends of the transistor Q1 through the transistor control unit to increase the lowest point voltage of the parasitic capacitor or reduce the highest point voltage of the parasitic capacitor, thereby reducing the turn-on time and turn-off time of the transistor Q1, increasing the lowest point voltage of the parasitic capacitor or reducing the highest point voltage of the parasitic capacitor, thereby reducing the influence of the parasitic capacitor in the transistor Q1, and ensuring the precise control and energy efficiency of the DC motor.

[0040] In some embodiments, the transistor Q1 is an N-channel MOS transistor.

[0041] In some embodiments, by connecting a correction capacitor C4 in parallel between the gate and source of the transistor Q1, when the driving wave is at a high level and conducting, the correction capacitor C4 is first pre-charged. When the transistor Q1 conducts, the bus voltage is applied across both sides of the coil. The correction capacitor C4 can stabilize the driving wave voltage, raise the voltage at the lowest point of the Miller plateau as much as possible, and prevent the transistor Q1 from being accidentally turned off. For details, please refer to Figure 1 , Figure 1 which is the first circuit schematic diagram of the transistor control circuit provided by the embodiment of the present application. The transistor control unit includes a correction capacitor C4, and the correction capacitor C4 is connected in parallel between the gate and source of the transistor Q1. When the transistor Q1 conducts, the correction capacitor C4 is used to provide current for the parasitic capacitance. The influence of the parasitic capacitance inside the transistor Q1 can be reduced, thereby preventing the transistor Q1 from being accidentally turned off, and ensuring the precise control and energy efficiency utilization of the DC motor.

[0042] Specifically, when Vgs < Vgs(th), the transistor Q1 is in the cut-off region, and the driving wave voltage across the transistor Q1 rises, and the correction capacitor C4 is gradually charged. When Vgs(mi) > Vgs > Vgs(th), the transistor Q1 gradually conducts, and the drain current of the transistor Q1 gradually increases. When the drain current rises to the maximum current, the transistor Q1 enters the saturation region. However, due to the parasitic capacitance between the gate and drain of the transistor Q1, at this time, the driving current of the transistor Q1 charges the parasitic capacitance. However, due to the addition of the correction capacitor C4, the correction capacitor C4 provides current for the parasitic capacitance, ensuring that the voltage fluctuation of the driving wave voltage is very small, weakening the voltage at the lowest point of the Miller plateau, and improving the driving wave waveform; where Vgs is the driving wave voltage across the transistor Q1, Vgs(th) is the critical threshold voltage when the transistor Q1 conducts, and Vgs(mi) is the Miller plateau voltage.

[0043] The critical threshold voltage when the transistor Q1 conducts is 2V, and the Miller plateau voltage is 5V.

[0044] Among them, the correction capacitor C4 is a high-frequency capacitor. Exemplarily, the capacitance of the correction capacitor C4 is greater than or equal to 0.01uf.

[0045] In some embodiments, the transistor control unit further includes an optocoupler U1 and a driving resistor R3. The sixth pin of the optocoupler U1 is connected to the gate of the transistor Q1, the fifth pin of the optocoupler U1 is connected to the source of the transistor Q1, one end of the driving resistor R3 is connected to the sixth pin of the optocoupler U1, and the other end of the driving resistor R3 is connected to the correction capacitor C4.

[0046] In some embodiments, the resistance value of the driving resistor R3 is 40R.

[0047] The eighth pin of the optocoupler U1 is connected to the positive voltage. A first capacitor C3 is provided between the eighth pin of the optocoupler U1 and the fifth pin of the optocoupler U1. The capacitance of the first capacitor C3 is 0.1 uf, and the first capacitor C3 is used for filtering. In some embodiments, the positive voltage is 15V.

[0048] The transistor control unit further includes a first resistor R1. The first resistor R1 is connected to the second pin of the optocoupler U1, and the first resistor R1 is a current-limiting resistor. In some embodiments, the resistance value of the first resistor R1 is 1k.

[0049] The transistor control unit further includes a second resistor R4. One end of the second resistor R4 is connected to the gate of the transistor Q1, and the other end of the second resistor R4 is connected to the source of the transistor Q1. The second resistor R4 is a pull-down resistor. In some embodiments, the resistance value of the second resistor R4 is 10k.

[0050] In some other embodiments, by applying a negative voltage power supply to the output end of the optocoupler U1, while the source end of the driving transistor Q1 is still connected to the power ground GND, it is ensured that the highest point voltage of the Miller plateau is lower than the turn-on voltage of the transistor Q1, preventing the phenomenon of mis-turn-on of the transistor Q1. For details, please continue to refer to Figure 2 , Figure 2 This is the second circuit schematic diagram of the transistor control circuit provided by the embodiment of the present application. The transistor control unit further includes an optocoupler U1 and a driving resistor R3. The sixth pin of the optocoupler U1 is connected to one end of the driving resistor R3, the other end of the driving resistor R3 is connected to the gate of the transistor Q1, the fifth pin of the optocoupler U1 is connected to the negative voltage, and the source of the transistor Q1 is grounded.

[0051] Exemplarily, connect the fifth pin of the optocoupler U1 to -5VDC, the eighth pin of the optocoupler U1 to +15VDC, and the source end of the transistor Q1 to the power ground GND. At this time, the -5V voltage can be regarded as the "power ground" of the driving wave voltage, so that the entire Miller plateau drops by 5V. When the Miller plateau is generated, the transistor Q1 is in the non-conducting state, making Vgs(mi) < Vgs(th), preventing the highest point voltage of the Miller plateau from turning on the transistor Q1 and reducing the switching loss of the transistor Q1.

[0052] In some other embodiments, the driving wave rising edge can also be optimized by setting a negative feedback signal amplifier. This signal amplifier can reduce the transmission delay from the input signal to the output signal, thereby reducing the turn-on or turn-off time of the transistor Q1 and eliminating the influence of the Miller plateau voltage.

[0053] In some other embodiments, due to the presence of parasitic capacitance at both ends of the gate and source of the transistor Q1, there is a capacitor discharge process when the transistor Q1 is turned off. In order to prevent the driving wave from being turned off slowly, the present application further optimizes the falling edge of the driving wave by connecting an anti-parallel diode D5 at both ends of the driving resistor R3 and the correction capacitor C4 so that the driving wave can quickly turn off the transistor Q1. For details, please continue to refer to Figure 3 , Figure 3 The third circuit diagram of the transistor control circuit provided in the embodiment of the present application, the transistor control unit includes an optocoupler U1, a driving resistor R3 and a diode D5, the sixth pin of the optocoupler U1 is connected to the gate of the transistor Q1, the fifth pin of the optocoupler U1 is connected to the source of the transistor Q1, one end of the driving resistor R3 is connected to the sixth pin of the optocoupler U1, the other end of the driving resistor R3 is connected to the gate of the transistor Q1, the positive electrode of the diode D5 is connected to the gate of the transistor Q1, and the negative electrode of the diode D5 is connected to the sixth pin of the optocoupler U1. The present application optimizes the rising edge of the driving wave, further connects a diode D5 in anti-parallel to both ends of the driving resistor R3, so that the parasitic capacitance voltage at both ends of the gate and source of the transistor Q1 is quickly discharged through the diode D5, and the transistor Q1 is quickly turned off, thereby reducing the influence of the parasitic capacitance in the transistor Q1.

[0054] Exemplarily, a diode D5 is connected in anti-parallel at both ends of the driving resistor R3, so that the parasitic capacitance voltage at both ends of the gate and source of the transistor Q1 is quickly discharged through the diode D5, and the transistor Q1 is quickly turned off. The model of the diode D5 may be IN4148.

[0055] It can be understood that the optimized transistor control circuit of the present application has a simple structure, optimizes the layout and wiring, and minimizes the length and impedance of the line, thereby reducing signal transmission delay and parasitic capacitance, reducing signal noise and attenuation, and reducing the impact of Miller platform voltage.

[0056] The embodiment of the present application also provides a transistor control circuit, which is applied to a DC motor. The transistor control circuit includes: a transistor Q1 and a transistor control unit, a parasitic capacitor is arranged between the gate and the drain of the transistor Q1, the transistor control unit is connected to the transistor Q1, the transistor control unit includes a transistor Q1, an optical coupler U1, a driving resistor R3 and a diode D5, the sixth pin of the optical coupler U1 is connected to the gate of the transistor Q1, the fifth pin of the optical coupler U1 is connected to the source of the transistor Q1, one end of the driving resistor R3 is connected to the sixth pin of the optical coupler U1, the other end of the driving resistor R3 is connected to the gate of the transistor Q1, the positive electrode of the diode D5 is connected to the gate of the transistor Q1, and the negative electrode of the diode D5 is connected to the sixth pin of the optical coupler U1. By connecting the diode D5 in anti-parallel at both ends of the driving resistor R3 and the correction capacitor C4 to optimize the falling edge of the driving wave, the driving wave can quickly turn off the transistor Q1, reduce the influence of the parasitic capacitor in the transistor Q1, and prevent the transistor Q1 from being turned off by mistake, thereby ensuring the precision control and energy efficiency of the DC motor.

[0057] Please continue reading Figure 4 , Figure 4 A circuit diagram of a DC motor drive circuit provided in an embodiment of the present application, an embodiment of the present application also provides a DC motor drive circuit, the DC motor drive circuit comprising a DC motor coil L and two transistor control circuits as described above, both transistor control circuits being connected to the DC motor coil L. Wherein, the specific conditions of the transistor control circuit can be found in the above content, which will not be repeated here. The DC motor drive circuit provided in this application will help improve system efficiency, reduce noise levels, extend equipment life, improve system stability and promote the realization of sustainable development goals. These improvements will have a positive impact on user comfort and satisfaction, and will also help reduce energy waste and protect the environment.

[0058] The transistor control circuits of the two transistors Q1 may be the same or different, and may be specifically configured according to actual conditions, and no specific limitation is made here.

[0059] The embodiment of the present application also provides an air conditioner, which includes the above-mentioned DC motor drive circuit. Although the utility model is disclosed as above, the utility model is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the utility model, so the protection scope of the utility model shall be based on the scope defined by the claims.

Claims

1. A transistor control circuit, applied to a DC motor, characterized in that: The transistor control circuit comprises: A transistor, wherein a parasitic capacitor is provided between a gate and a drain of the transistor; A transistor control unit, the transistor control unit is connected to the transistor, the transistor control unit includes a correction capacitor, the correction capacitor is connected in parallel between the gate and source of the transistor, when the transistor is turned on, the correction capacitor is used to provide current for the parasitic capacitor.

2. The transistor control circuit according to claim 1, characterized in that: The transistor control unit also includes an optocoupler and a driving resistor, the sixth pin of the optocoupler is connected to the gate of the transistor, the fifth pin of the optocoupler is connected to the source of the transistor, one end of the driving resistor is connected to the sixth pin of the optocoupler, and the other end of the driving resistor is connected to the correction capacitor.

3. The transistor control circuit according to claim 1, characterized in that: The transistor control unit also includes an optocoupler and a driving resistor, the sixth pin of the optocoupler is connected to one end of the driving resistor, the other end of the driving resistor is connected to the gate of the transistor, the fifth pin of the optocoupler is connected to a negative voltage, and the source of the transistor is grounded.

4. The transistor control circuit according to claim 3, characterized in that: The eighth pin of the optocoupler is connected to a positive voltage, and a first capacitor is arranged between the eighth pin of the optocoupler and the fifth pin of the optocoupler.

5. The transistor control circuit according to any one of claims 1 to 4, characterized in that: The capacity of the correction capacitor is greater than or equal to 0.01uf.

6. The transistor control circuit according to any one of claims 1 to 4, characterized in that: The transistor control unit includes an optocoupler, a driving resistor and a diode, the sixth pin of the optocoupler is connected to the gate of the transistor, the fifth pin of the optocoupler is connected to the source of the transistor, one end of the driving resistor is connected to the sixth pin of the optocoupler, the other end of the driving resistor is connected to the gate of the transistor, the anode of the diode is connected to the gate of the transistor, and the cathode of the diode is connected to the sixth pin of the optocoupler.

7. A transistor control circuit, applied to a DC motor, characterized in that: The transistor control circuit comprises: A transistor, wherein a parasitic capacitor is provided between a gate and a drain of the transistor; A transistor control unit, wherein the transistor control unit is connected to the transistor, and the transistor control unit includes an optocoupler, a driving resistor and a diode, wherein the sixth pin of the optocoupler is connected to the gate of the transistor, the fifth pin of the optocoupler is connected to the source of the transistor, one end of the driving resistor is connected to the sixth pin of the optocoupler, the other end of the driving resistor is connected to the gate of the transistor, the positive electrode of the diode is connected to the gate of the transistor, and the negative electrode of the diode is connected to the sixth pin of the optocoupler.

8. A DC motor drive circuit, characterized in that: The DC motor drive circuit comprises: DC motor coil; Two transistor control circuits according to any one of claims 1 to 7, both of which are connected to the DC motor coil.

9. An air conditioner, characterized in that: The air conditioner comprises the DC motor driving circuit as claimed in claim 8.

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