Drive control circuit and air conditioner

Abstract

The present invention provides a drive control circuit and an air conditioner. The drive control circuit includes: a resistive absorption circuit for absorbing surge signals on the bus line, the resistive absorption circuit being connected in parallel with the bus capacitor; a switching element for regulating the process of the resistive absorption circuit absorbing surge signals, the switching element being connected in series with the resistive absorption circuit; and a control chip for determining whether to output a preset pulse width modulation signal to the switching element according to the magnitude relationship between the bus voltage and a preset threshold, the control chip being connected to the switching element and the sampling circuit respectively. By using the drive control circuit provided by the present invention, the situation that the bus capacitor has poor absorption of surge signals can be effectively alleviated, thereby improving the stability and reliability of the bus voltage. At the same time, using the preset pulse width modulation signal to control the switching element can effectively reduce the requirement for the instantaneous overload capacity of the resistive absorption circuit. When consuming the same surge energy, the cost is lower and the control is simpler.

Description

[0001] This application claims the priority of a Chinese patent application with the application number "2019100417084" and the invention title "Drive Control Circuit, Air Conditioner" submitted to the Chinese Patent Office on January 16, 2019, the entire content of which is incorporated herein by reference. Technical Field

[0002] The present invention relates to the technical field of air conditioners, and in particular, to a drive control circuit and an air conditioner. Background Art

[0003] Currently, a large number of variable frequency air conditioner controllers adopt the AC-DC-AC (alternating current - direct current - alternating current) topology structure, and its structural schematic diagram is as Figure 1 shown, mainly including: an AC power supply module 10', a power filter module 12', a rectification module 14', a filter module 16', an inverter module 18' and a load 20'.

[0004] Since the filter module 16' needs to filter the rectified power frequency signal, large-capacity electrolytic capacitors are often used as the main filtering components. With the improvement of cost and reliability requirements, the control scheme of reducing the capacity of electrolytic capacitors or even eliminating electrolytic capacitors has gradually matured.

[0005] For the control scheme without electrolytic capacitors, a small-capacity thin-film capacitor is generally used to replace the electrolytic capacitor. Due to the reduction of the bus capacitor capacity, the absorption ability for abnormal surges becomes poor, resulting in too high a DC bus voltage and damaging components. Summary of the Invention

[0006] The present invention aims to solve at least one of the technical problems existing in the prior art or related technologies.

[0007] To this end, one aspect of the present invention is to provide a drive control circuit.

[0008] Another aspect of the present invention is to provide an air conditioner.

[0009] In view of this, one aspect of the present invention provides a drive control circuit, including: an inverter bridge for driving and controlling the operation of a load, the inverter bridge being connected between a high-voltage bus and a low-voltage bus; a reactor for absorbing surge signals generated during the operation of the drive control circuit to drive the load, the reactor being connected between the power grid and the load; a bus capacitor for providing the starting voltage required for the load to be powered on, and the bus capacitor is also used to absorb surge signals, the bus capacitor being connected to the bus line on the input side of the inverter bridge; a sampling circuit for sampling the bus voltage; the drive control circuit further includes: a resistive absorption circuit for absorbing surge signals on the bus line, the resistive absorption circuit being connected in parallel with the bus capacitor; a switching element for regulating the process of the resistive absorption circuit absorbing surge signals, the switching element being connected in series with the resistive absorption circuit; a control chip for determining whether to output a preset pulse-width modulation signal to the switching element according to the magnitude relationship between the bus voltage and a preset threshold, the control chip being connected to the switching element and the sampling circuit respectively.

[0010] For the drive control circuit provided by the present invention, the surge energy mainly comes from the power input, the motor winding when the prototype fails and stops, the continuous current of the AC-DC side inductor, and the kinetic energy of the motor. When a surge signal comes, since the ability of the bus capacitor (such as a film capacitor or a small-capacity electrolytic capacitor) to absorb surges is limited, the bus voltage will rise rapidly. Once the bus voltage exceeds the set protection threshold, the components will be damaged. To protect the components from high-voltage damage (mainly components such as intelligent power modules and capacitors), the switching element needs to act to enable the resistive absorption circuit to start absorbing surges. Specifically, the sampling circuit samples the bus voltage in real time, and the control chip obtains the real-time bus voltage. By comparing the bus voltage with the preset threshold, it can be determined whether the bus voltage is overvoltage. It can be understood that in the case of overvoltage, a preset pulse-width modulation signal (the preset pulse-width modulation signal is a pulse-width modulation signal in the form of a fixed carrier frequency (such as 40K, which can be other values) and a fixed duty cycle (such as 50%, which can be other duty cycle values)) is output to the switching element. The switching element acts, and the resistive absorption circuit starts to absorb surges, and the bus voltage will drop rapidly; when the control chip determines that the bus voltage drops to a reasonable range, this range can be set according to the actual situation, and the control chip turns off the output of the preset pulse-width modulation signal, and the resistive absorption circuit ends the surge absorption process of this stage. Through the drive control circuit provided by the present invention, the situation that the bus capacitor has poor absorption of surge signals can be effectively alleviated, thereby improving the stability and reliability of the bus voltage. At the same time, using the preset pulse-width modulation signal to control the switching element can effectively reduce the instantaneous overload capacity requirement of the resistive absorption circuit, consume the same surge energy, and have a lower cost and simple control. Among them, the selection of the preset threshold has an upper limit set according to the withstand voltage of the components and a lower limit to avoid mis-triggering of the switching element within the normal power supply range.

[0011] Among them, there is a power amplifier circuit connected in series between the control chip and the switching element. The control signal output by the control circuit is amplified through the power amplifier circuit so that the control chip can drive the switching element.

[0012] In addition, according to the above-mentioned drive control circuit provided by the present invention, the following additional technical features may also be included:

[0013] In the above technical solution, preferably, the drive control circuit further includes: a capacitive absorption circuit for absorbing surge signals between the high-voltage bus and the low-voltage bus, the capacitive absorption circuit being connected in parallel with the bus capacitor; a unidirectional conduction element for regulating the process of the capacitive absorption circuit absorbing surge signals, the unidirectional conduction element being connected in series with the capacitive absorption circuit.

[0014] In this technical solution, the drive control circuit further includes a capacitive absorption circuit and a unidirectional conduction element. The unidirectional conduction element is used as an isolation element between the capacitive absorption circuit and the bus capacitor to regulate the process of the capacitive absorption circuit absorbing surge signals. Specifically, if the surge absorption circuit composed of the unidirectional conduction element and the capacitive absorption circuit is in an uncontrolled form, when there is a surge signal higher than the maximum value of the bus voltage, the unidirectional conduction element conducts, and the capacitive absorption circuit and the bus capacitor act simultaneously to jointly absorb the surge signal; if it is in a controllable form, when the current bus voltage is greater than a certain fixed value (which can be set according to actual conditions), the unidirectional conduction element conducts, and the surge signal will enter the capacitive absorption circuit at the fastest speed first, thereby stabilizing the bus voltage. Among them, the unidirectional conduction element is an element with unidirectional conduction characteristics, such as a diode, etc.

[0015] In this solution, preferably, the unidirectional conduction element is a diode, that is, an uncontrolled form of surge absorption circuit is composed of a diode and a capacitive absorption circuit.

[0016] In any of the above technical solutions, preferably, the resistive absorption circuit includes: a first resistive element for absorbing surge signals, the first resistive element being connected in series with the switching element; a switching element specifically for controlling the process of the first resistive element absorbing surge signals.

[0017] In this technical solution, the resistive absorption circuit includes a first resistive element. By connecting the first resistive element between the high-voltage bus and the low-voltage bus to absorb the surge signals on the bus, rapid absorption of the surge signals can be achieved, ensuring a rapid drop in the bus voltage. Among them, the resistance value of the first resistive element is related to the bus voltage protection threshold and the over-current capacity of the switching element. Preferably, the first resistive element is one or more resistors connected in series, and the resistor can be an inductive resistor or a non-inductive resistor, which is not specifically limited herein. Among them, the switching element includes a triode, a relay, a power switching device, etc.

[0018] In any of the above technical solutions, preferably, the resistive absorption circuit further includes: a discharge element, configured to release the spike voltage of the first resistive element, and the discharge element is connected in parallel with the first resistive element.

[0019] In this technical solution, the resistive absorption circuit further includes a discharge element, which is connected in parallel with the first resistive element and serves as a release loop for the spike voltage of the first resistive element, preventing the first resistive element from generating a spike voltage when the switching element is turned off, thereby affecting the drive control circuit or causing component damage.

[0020] It should be noted that the selection of the discharge element is related to the inductance and resistance value of the first resistive element. Preferably, the capacitance of the discharge element is positively correlated with the inductance of the first resistive element, that is, the smaller the inductance of the first resistive element, the smaller the capacitance of the discharge element. If the inductance of the first resistive element is small enough to be negligible or non-existent, for example, the first resistive element is composed of one or more series-connected non-inductive resistors, then the discharge element can be not used, and the first resistive element alone can be used as the absorption element. Among them, the composition of the discharge element includes but is not limited to the following three methods:

[0021] Optionally, the discharge element is a diode, or a series combination of a diode and a resistor, where the conduction direction of the diode is opposite to the current direction flowing through the first resistive element.

[0022] Optionally, the discharge element is a capacitor.

[0023] Optionally, the discharge element includes a resistor and a capacitor connected in series, that is, a series RC resonant circuit is used to release the spike voltage of the first resistive element.

[0024] In any of the above technical solutions, preferably, the capacitive absorption circuit includes: a first capacitive element, configured to absorb surge signals, and the first capacitive element is connected in series with a unidirectional conduction element; a second resistive element, configured to release the surge signals in the first capacitive element, and the second resistive element is connected in parallel with the first capacitive element.

[0025] In this technical solution, the capacitive absorption circuit includes a first capacitive element and a second resistive element connected in parallel, and the number of the first capacitive element and the second resistive element is one or more.

[0026] Optionally, the number of the second resistive elements corresponds one-to-one to the number of the first capacitive elements, and the first capacitive element is connected in parallel with the second resistive element. When the number of the first capacitive elements is multiple, the second resistive element acts as a balancing resistor and also serves as an electrolytic capacitor discharge function.

[0027] Optionally, the number of the second resistive elements is multiple, and the multiple second resistive elements are connected in series and then connected in parallel with the first capacitive element.

[0028] In any of the above technical solutions, preferably, the capacitive absorption circuit includes: a second capacitive element for absorbing surge signals on the high-voltage bus and the low-voltage bus, and the second capacitive element is connected in series with the first capacitive element; a third resistive element for releasing the surge signals in the second capacitive element, and the third resistive element is connected in parallel with the second capacitive element.

[0029] In this technical solution, the capacitive absorption circuit further includes a second capacitive element and a third resistive element connected in parallel, and the number of the second capacitive element and the third resistive element is one or more. Among them, the capacitance values of the second capacitive element and the first capacitive element may be the same or different. Preferably, the resistance values of the second resistive element and the third resistive element are the same to balance the voltages of the first capacitive element and the second capacitive element and also serve the function of electrolytic capacitor discharging.

[0030] In any of the above technical solutions, preferably, the drive control circuit further includes: a fourth resistive element for limiting the current flowing through the capacitive absorption circuit, and the fourth resistive element is connected in series in the branch where the capacitive absorption circuit and the unidirectional conduction element are located.

[0031] In this technical solution, the drive control circuit further includes a fourth resistive element for limiting the current flowing through the capacitive absorption circuit. Among them, according to the different capacitance values of the first capacitive element and the second capacitive element, the selection of the fourth resistive element is also different.

[0032] In any of the above technical solutions, preferably, the control chip is specifically configured to: output a preset pulse width modulation signal to the switching element based on the bus voltage being greater than or equal to a first preset threshold; stop outputting the preset pulse width modulation signal based on the bus voltage being less than a second preset threshold; where the first preset threshold is greater than the second preset threshold.

[0033] In this technical solution, the first preset threshold and the second preset threshold are bus voltage protection thresholds set for the software. The first preset threshold and the second preset threshold respectively correspond to the conduction threshold and the turn-off threshold of the switching element. The bus voltage is compared with the first preset threshold and the second preset threshold respectively. When the bus voltage is greater than or equal to the first preset threshold, the control chip determines that the bus voltage is overvoltage and outputs a preset pulse width modulation signal to control the conduction of the switching element. When the bus voltage is less than the second preset threshold, the control chip determines that the bus voltage has dropped to a reasonable range, thereby turning off the switching element.

[0034] In any of the above technical solutions, preferably, the drive control circuit further includes: a comparison circuit for outputting a corresponding level signal to the control chip according to the bus voltage, the input end of the comparison circuit is connected to the output end of the sampling circuit, and the output end of the comparison circuit is connected to the control chip; the control chip is further configured to determine whether to output a preset pulse width modulation signal to the switching element according to the level signal.

[0035] In this technical solution, considering the delay of software sampling, the hardware can notify the software to perform PWM output as quickly as possible. Therefore, the hardware comparison circuit determines whether the bus voltage is overvoltage and outputs a corresponding level signal to the control chip. The control chip determines whether the bus voltage is overvoltage according to the level signal, so as to turn on or off the switching element.

[0036] In any of the above technical solutions, preferably, the comparison circuit is specifically configured to: output a first level signal based on the bus voltage being greater than or equal to a third preset threshold; and output a second level signal based on the bus voltage being less than or equal to a fourth preset threshold; the control chip is specifically configured to: output a preset pulse width modulation signal to the switching element when receiving the first level signal or a flip signal that changes from the second level to the first level; the third preset threshold is greater than the first preset threshold; the third preset threshold is greater than the fourth preset threshold, and the fourth preset threshold is greater than the first preset threshold.

[0037] In this technical solution, the third and fourth preset thresholds are bus voltage protection thresholds set for the hardware comparison circuit. When the bus voltage is greater than or equal to the third preset threshold, the comparison circuit generates an overvoltage signal and sends it to the control chip. Specifically, it outputs a first level signal to the control chip; when the bus voltage is less than or equal to the fourth preset threshold, it outputs a second level signal to the control chip. When the control chip receives the first level signal or a flip signal that changes from the second level to the first level, it outputs a preset pulse width modulation signal to the switching element. Specifically, it outputs a switching signal in the form of a preset duty cycle at a preset carrier frequency to the switching element, and the switching element conducts, and the resistive absorption circuit starts to intervene, and the bus voltage will quickly drop. When the control chip detects that the bus voltage drops to the fourth preset threshold, it turns off the output of the preset pulse width modulation signal, the switching element disconnects, and the resistive absorption circuit ends the surge absorption process of this stage.

[0038] Assume that the initial level is high level, then the first level signal is low level, and the second level signal is high level. On the contrary, if the initial level is low level, then the first level signal is high level, and the second level signal is low level.

[0039] In any of the above technical solutions, preferably, the drive control circuit further includes a rectifier circuit. The rectifier circuit rectifies the AC signal and outputs it as a bus signal. The bus signal is output to the bus capacitor, the inverter bridge and the load through the high-voltage bus and the low-voltage bus. Among them, the control chip controls the conduction state of the switching element according to the AC signal.

[0040] In this technical solution, the AC voltage signal is processed into a bus voltage signal by the rectifier circuit. Both the bus voltage signal and the AC voltage signal can be used as the determination conditions for controlling the conduction or cutoff of the switching element.

[0041] In any of the above technical solutions, preferably, the control chip controls the on - off state of the switching element according to the AC signal as follows: comparing the voltage value corresponding to the AC signal collected in real - time with a preset fifth threshold, if it is determined that the voltage value is greater than or equal to the fifth threshold, then control the switching element to conduct; comparing the voltage value corresponding to the AC signal with a preset sixth threshold, if it is determined that the voltage value is less than or equal to the sixth threshold, then control the switching element to cut off. Wherein, the fifth threshold and the sixth threshold are the on - conduction threshold and the off - conduction threshold of the switching element preset according to the AC signal. In addition, for the comparison circuit, the on - conduction threshold (seventh threshold) and the off - conduction threshold (eighth threshold) of the switching element can also be preset according to the AC signal. The seventh threshold is greater than the eighth threshold, the eighth threshold is greater than the fifth threshold, and the fifth threshold is greater than the sixth threshold.

[0042] In any of the above technical solutions, preferably, the bus capacitor is a thin - film capacitor.

[0043] In any of the above technical solutions, preferably, the selection of the preset pulse - width modulation signal (including the carrier frequency and the duty cycle) is related to the first preset threshold, the resistance value, the rated power and the instantaneous overload capacity of the first resistive element.

[0044] In any of the above technical solutions, the capacitance value of the bus capacitor is less than the preset capacity, and the preset capacity is calculated according to the following formula:

[0045]

[0046] where C dc is the preset capacity, L S is the total inductance value of the DC side of the equivalent drive control circuit, P L is the load power of the drive control circuit, R S is the total resistance of the DC side of the equivalent drive control circuit, v dc0 is the average value of the bus voltage. For example, taking the 7P prototype as an example, according to this calculation formula, C dc must be greater than 840 uF, the preset capacity is above 840 uF, and 1230 uF is used in the specific implementation.

[0047] On the other hand, the present invention proposes an air conditioner, including: a motor; a drive control circuit as described in any of the above technical solutions, the signal input end of the motor is connected to the drive control circuit, and the drive signal output by the drive control circuit is used to drive the motor to operate.

[0048] The air conditioner provided by the present invention includes the drive control circuit as described in any of the above technical solutions, and thus has all the technical effects of the drive control circuit, which will not be elaborated here.

[0049] Additional aspects and advantages of the present invention will become apparent in the following description section or will be learned through the practice of the present invention. Description of the Drawings

[0050] The above and / or additional aspects and advantages of the present invention will become apparent and be readily understood from the description of embodiments in conjunction with the following drawings, where:

[0051] Figure 1 A schematic structural diagram of a controller of a variable-frequency air conditioner in the prior art is shown;

[0052] Figure 2 A schematic structural diagram of a drive control circuit according to an embodiment of the present invention is shown;

[0053] Figure 3 A schematic structural diagram of a drive control circuit according to another embodiment of the present invention is shown;

[0054] Figure 4 A schematic structural diagram of a drive control circuit according to still another embodiment of the present invention is shown;

[0055] Figure 5 A schematic structural diagram of a drive control circuit according to yet another embodiment of the present invention is shown;

[0056] Figure 6 A schematic structural diagram of a drive control circuit according to yet another embodiment of the present invention is shown;

[0057] Figure 7 A schematic structural diagram of a drive control circuit according to yet another embodiment of the present invention is shown;

[0058] Figure 8 A schematic diagram of absorbing surges according to an embodiment of the present invention is shown.

[0059] Wherein, Figure 1 The corresponding relationship between the reference numerals and the component names in the drawings is as follows:

[0060] 10' AC power supply module, 12' power filter module, 14' rectification module, 16' filter module, 18' inversion module, 20' load;

[0061] Wherein, Figures 2 to 7 The corresponding relationship between the reference numerals and the component names in the drawings is as follows:

[0062] 10 Inverter bridge, 12 Reactor, 14 Bus capacitor, 16 Resistive absorption circuit, 18 Switching element, 20 Comparison circuit, 22 Control chip, 24 Capacitive absorption circuit, 26 Unidirectional conduction element, 28 First resistive element, 30 Discharge element, 32 First capacitive element, 34 Second resistive element, 36 Second capacitive element, 38 Third resistive element, 40 Fourth resistive element, 42 Rectifier circuit. Detailed implementation manners

[0063] In order to more clearly understand the above objects, features and advantages of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific implementation manners. It should be noted that, without conflict, the embodiments of the present application and the features in the embodiments can be combined with each other.

[0064] In the following description, many specific details are set forth in order to fully understand the present invention. However, the present invention can also be implemented in other ways different from those described herein. Therefore, the protection scope of the present invention is not limited by the specific embodiments disclosed below.

[0065] The following refers to Figures 2 to 8 Describe a drive control circuit and an air conditioner according to some embodiments of the present invention.

[0066] An embodiment of one aspect of the present invention provides a drive control circuit.

[0067] As Figure 2 shown, a schematic structural diagram of a drive control circuit according to a first embodiment of the present invention. Among them, the drive control circuit includes: an inverter bridge 10 for driving and controlling a load to operate, and the inverter bridge 10 is connected between a high-voltage bus and a low-voltage bus; a reactor 12 for absorbing surge signals generated during the process of driving and controlling the load to operate by the drive control circuit, and the reactor 12 is connected between the power grid and the load; a bus capacitor 14 for providing a starting voltage required for the load to be powered on, and the bus capacitor 14 is also used for absorbing surge signals, and the bus capacitor 14 is connected to the bus line on the input side of the inverter bridge 10; a sampling circuit for sampling the bus voltage; the drive control circuit further includes: a resistive absorption circuit 16 for absorbing surge signals on the bus line, and the resistive absorption circuit 16 is connected in parallel with the bus capacitor 14; a switching element 18 for regulating the process of the resistive absorption circuit 16 absorbing surge signals, and the switching element 18 is connected in series with the resistive absorption circuit 16. When the switching element 18 is turned on, the resistive absorption circuit 16 absorbs surge signals. When the switching element 18 is turned off, the resistive absorption circuit 16 stops absorbing surge signals; a control chip 22 for determining whether to output a preset pulse width modulation signal to the switching element 18 according to the magnitude relationship between the bus voltage and a preset threshold value, and the control chip 22 is respectively connected to the switching element 18 and the sampling circuit.

[0068] In the driving control circuit provided by the embodiment of the present invention, the surge energy mainly comes from the power input, the motor winding when the prototype fails and stops, the freewheeling of the AC-DC side inductance, and the kinetic energy of the motor. When a surge signal comes, since the bus capacitor 14 (such as a thin film capacitor or a small-capacity electrolytic capacitor) has limited ability to absorb surges, the bus voltage will rise rapidly. Once the bus voltage exceeds the set protection threshold, it may damage the components. To protect the components from high-voltage damage (mainly components such as intelligent power modules and capacitors), the switching element 18 needs to act to enable the resistive absorption circuit 16 to start absorbing surges. Specifically, the bus voltage is sampled in real time through the sampling circuit, and the control chip 22 obtains the real-time bus voltage. By comparing the bus voltage with the preset threshold, it can be determined whether the bus voltage is overvoltage. Understandably, in the case of overvoltage, a preset pulse width modulation signal (the preset pulse width modulation signal is a pulse width modulation signal in the form of a fixed carrier frequency (such as 40K, which can be other values) and a fixed duty cycle (such as 50%, which can be other duty cycle values)) is output to the switching element 18. The switching element 18 acts, and the resistive absorption circuit 16 starts to absorb surges, and the bus voltage will drop rapidly; when the control chip determines that the bus voltage drops to a reasonable range, which can be set according to the actual situation, the control chip 22 turns off the output of the preset pulse width modulation signal, and the resistive absorption circuit 16 ends the surge absorption process of this stage. Through the driving control circuit provided by the present invention, the situation that the bus capacitor has poor absorption of surge signals can be effectively alleviated, thereby improving the stability and reliability of the bus voltage. At the same time, using the preset pulse width modulation signal to control the switching element 18 can effectively reduce the instantaneous overload capacity requirement of the resistive absorption circuit, consume the same surge energy, with lower cost and simpler control. Among them, the upper limit of the preset threshold is set according to the withstand voltage of the components, and the lower limit is to avoid mis-triggering of the switching element within the normal power supply range.

[0069] Among them, a power amplifier circuit is connected in series between the control chip 22 and the switching element 18 to amplify the control signal output by the control circuit so that the control chip 22 can drive the switching element 18.

[0070] In an embodiment of the present invention, preferably, the driving control circuit further includes: a capacitive absorption circuit 24 for absorbing surge signals on the bus line, the capacitive absorption circuit 24 is connected in parallel with the bus capacitor 14; a unidirectional conduction element 26 for regulating the process of the capacitive absorption circuit 24 absorbing the surge signals, the unidirectional conduction element 26 is connected in series with the capacitive absorption circuit 24. When the unidirectional conduction element 26 conducts, the capacitive absorption circuit 24 absorbs surge signals, and when the unidirectional conduction element 26 is cut off, the capacitive absorption circuit 24 stops absorbing surge signals.

[0071] In this embodiment, the drive control circuit further includes a capacitive absorption circuit 24 and a unidirectional conduction element 26. The unidirectional conduction element 26 is used as an isolation element between the capacitive absorption circuit 24 and the bus capacitor 14, so as to limit the absorption process of the capacitive absorption circuit 24 for surge signals. Specifically, if the surge absorption circuit composed of the unidirectional conduction element 26 and the capacitive absorption circuit 24 is in an uncontrolled form, when there is a surge signal higher than the maximum value of the current bus voltage, the unidirectional conduction element 26 conducts, and the capacitive absorption circuit 24 and the bus capacitor 14 act simultaneously to jointly absorb the surge signal; if it is in a controllable form, when the current bus voltage is greater than a certain fixed value (which can be set according to the actual situation), the unidirectional conduction element 26 conducts, and the surge signal will enter the capacitive absorption circuit 24 first at the fastest speed, thereby stabilizing the bus voltage and stopping the motor at the same time. Among them, the unidirectional conduction element 26 is an element with unidirectional conduction characteristics, such as a diode, etc. Specifically, as Figure 2 shown, the unidirectional conduction element 26 is a diode, that is, an uncontrolled surge absorption circuit is composed of the diode and the capacitive absorption circuit 24.

[0072] In another embodiment of the present invention, the unidirectional conduction element 26 can also be replaced by a switching element, such as a triode, a relay, etc.

[0073] In an embodiment of the present invention, as Figure 2 shown, preferably, the resistive absorption circuit 16 includes: a first resistive element 28 for absorbing surge signals, and the first resistive element 28 is connected in series with the switching element 18; the switching element 18 is specifically used to control the absorption process of the first resistive element 28 for surge signals.

[0074] In this embodiment, the resistive absorption circuit 16 includes a first resistive element 28. By connecting the first resistive element 28 between the high-voltage bus and the low-voltage bus to absorb the surge signal on the bus, the rapid absorption of the surge signal can be realized, and the rapid drop of the bus voltage can be ensured. Among them, the resistance value of the first resistive element 28 is related to the bus voltage protection threshold and the over-current capacity of the switching element 18. Preferably, the first resistive element 28 is one or more resistors connected in series, and the resistor can be an inductive resistor or a non-inductive resistor, which is not specifically limited herein. Among them, the switching element includes a triode, a relay, etc.

[0075] In another embodiment of the present invention, as Figure 3 、 Figure 4 shown, preferably, the resistive absorption circuit 16 further includes: a discharge element 30 for releasing the spike voltage of the first resistive element 28, and the discharge element 30 is connected in parallel with the first resistive element 28.

[0076] In this embodiment, the resistive absorption circuit 16 further includes a discharge element 30. The discharge element 30 is connected in parallel with the first resistive element 28 and serves as a discharge loop for the spike voltage of the first resistive element 28, preventing the first resistive element 28 from generating a spike voltage when the switching element 18 is turned off, thereby affecting the drive control circuit or damaging components.

[0077] It should be noted that the selection of the discharge element 30 is related to the inductance and resistance value of the first resistive element 28. Preferably, the capacitance of the discharge element 30 is positively correlated with the inductance of the first resistive element 28, that is, the smaller the inductance of the first resistive element 28, the smaller the capacitance of the discharge element 30. If the inductance of the first resistive element 28 is small enough to be negligible or non-existent, for example, the first resistive element 28 consists of one or more series-connected non-inductive resistors, then the discharge element 30 can be not used, and the first resistive element 28 alone can be used as the absorption element.

[0078] In an embodiment of the present invention, as Figure 2 shown, preferably, an antiparallel diode is used to release the spike voltage of the first resistive element 28.

[0079] Optionally, the discharge element 30 includes a diode and a resistor connected in series, wherein the conduction direction of the diode is opposite to the current direction flowing through the first resistive element 28.

[0080] Optionally, the discharge element 30 is a capacitor.

[0081] Optionally, the discharge element 30 includes a resistor and a capacitor connected in series, that is, a series-connected RC resonance circuit is used to release the spike voltage of the first resistive element 28.

[0082] In an embodiment of the present invention, as Figure 2 shown, preferably, the capacitive absorption circuit 24 includes: a first capacitive element 32 for absorbing surge signals, the first capacitive element 32 is connected in series with a unidirectional conduction element 26; a second resistive element 34 for releasing the surge signals in the first capacitive element 32, the second resistive element 34 is connected in parallel with the first capacitive element 32.

[0083] In this embodiment, the capacitive absorption circuit 24 includes the first capacitive element 32 and the second resistive element 34 connected in parallel. The number of the first capacitive element 32 and the second resistive element 34 is one or more. Specifically, as Figure 2 shown, the number of both the first capacitive element 32 and the second resistive element 34 is one.

[0084] Optionally, the number of the second resistive elements 34 corresponds one-to-one to the number of the first capacitive elements 32, and the first capacitive elements 32 and the second resistive elements 34 are connected in parallel. When the number of the first capacitive elements 32 is multiple, the second resistive elements 34 function as balancing resistors and also function as electrolytic capacitor discharge resistors.

[0085] Optionally, the number of the second resistive elements 34 is multiple, and the multiple second resistive elements 34 are connected in series and then connected in parallel with the first capacitive element 32.

[0086] In an embodiment of the present invention, as Figure 2 shown, preferably, the capacitive absorption circuit 24 includes: a second capacitive element 36 for absorbing surge signals on the high-voltage bus and the low-voltage bus, and the second capacitive element 36 is connected in series with the first capacitive element 32; a third resistive element 38 for releasing the surge signals in the second capacitive element 36, and the third resistive element 38 is connected in parallel with the second capacitive element 36.

[0087] In this embodiment, the capacitive absorption circuit 24 further includes a second capacitive element 36 and a third resistive element 38 connected in parallel, and the number of the second capacitive elements 36 and the third resistive elements 38 is one or more. Specifically, as Figure 2 shown, the number of the second capacitive elements 36 and the third resistive elements 38 is both one. Wherein, the capacitance values of the second capacitive element 36 and the first capacitive element 32 may be the same or different. Preferably, the resistance values of the second resistive element 34 and the third resistive element 38 are the same to balance the voltages of the first capacitive element 32 and the second capacitive element 36, and also function as electrolytic capacitor discharge resistors.

[0088] In an embodiment of the present invention, as Figure 2 shown, preferably, the drive control circuit further includes: a fourth resistive element 40 for limiting the current flowing through the capacitive absorption circuit 24, and the fourth resistive element 40 is connected in series in the branch where the capacitive absorption circuit 24 and the unidirectional conduction element 26 are located.

[0089] In this embodiment, the drive control circuit further includes a fourth resistive element 40 to limit the current flowing through the capacitive absorption circuit 24 through the fourth resistive element 40. Wherein, according to the different capacitance values of the first capacitive element 32 and the second capacitive element 36, the selection of the fourth resistive element 40 is also different.

[0090] In an embodiment of the present invention, preferably, the control chip 22 is specifically configured to: output a preset pulse width modulation signal to the switching element based on the condition that the bus voltage is greater than or equal to a first preset threshold; stop outputting the preset pulse width modulation signal based on the condition that the bus voltage is less than a second preset threshold; wherein the first preset threshold is greater than the second preset threshold.

[0091] In this embodiment, the first preset threshold and the second preset threshold are bus voltage protection thresholds set for the software. The first preset threshold and the second preset threshold respectively correspond to the conduction threshold and the turn-off threshold of the switching element 18. The bus voltage is compared with the first preset threshold and the second preset threshold respectively. When the bus voltage is greater than or equal to the first preset threshold, the control chip 22 determines that the bus voltage is overvoltage and outputs a preset pulse width modulation signal to control the conduction of the switching element 18. When the bus voltage is less than the second preset threshold, the control chip 22 determines that the bus voltage has dropped to a reasonable range, and thus turns off the switching element 18.

[0092] In an embodiment of the present invention, as Figure 2 shown, preferably, the drive control circuit further includes: a comparison circuit 20 for outputting a corresponding level signal to the control chip 22 according to the bus voltage. The input end of the comparison circuit 20 is connected to the output end of the sampling circuit, and the output end of the comparison circuit 20 is connected to the control chip 22; the control chip 22 is further configured to determine whether to output a preset pulse width modulation signal to the switching element 18 according to the level signal.

[0093] In this embodiment, considering the delay of software sampling, the hardware can notify the software to perform PWM output as quickly as possible. Therefore, the hardware comparison circuit 20 determines whether the bus voltage is overvoltage and outputs a corresponding level signal to the control chip 22. The control chip 22 determines whether the bus voltage is overvoltage according to the level signal, and thus turns on or off the switching element 18.

[0094] In an embodiment of the present invention, preferably, the comparison circuit 20 is specifically configured to: output a first level signal when the bus voltage is greater than or equal to a third preset threshold; and output a second level signal when the bus voltage is less than or equal to a fourth preset threshold; the control chip 22 is specifically configured to: output a preset pulse width modulation signal to the switching element when receiving the first level signal or a flip signal that changes from the second level signal to the first level signal; the third preset threshold is greater than the first preset threshold; the third preset threshold is greater than the fourth preset threshold, and the fourth preset threshold is greater than the first preset threshold.

[0095] In this embodiment, the third and fourth preset thresholds are bus voltage protection thresholds set for the hardware comparison circuit 20. When the bus voltage is greater than or equal to the third preset threshold, the comparison circuit 20 generates an overvoltage signal and transmits it to the control chip 22. Specifically, it outputs a first-level signal to the control chip 22. When the bus voltage is less than or equal to the fourth preset threshold, it outputs a second-level signal to the control chip. Upon receiving the first-level signal or a flip signal from the second level to the first level, the control chip 22 outputs a preset pulse-width modulation signal to the switching element. Specifically, it outputs a control signal with a preset duty cycle at a preset carrier frequency to the switching element. The switching element turns on, the resistive absorption circuit begins to intervene, and the bus voltage drops rapidly. When the control chip 22 detects that the bus voltage has dropped to the fourth preset threshold, it shuts off the preset pulse-width modulation signal, disconnects the switching element 18, and the resistive absorption circuit 16 ends the surge absorption process at this stage.

[0096] Assuming that the initial level is high, the first level signal is low and the second level signal is high. Conversely, if the initial level is low, the first level signal is high and the second level signal is low. In another embodiment of the present invention, Figure 5 As shown, the drive control circuit uses the resistive absorption circuit 16 and the capacitive absorption circuit 24 at the same time, adopts the switching element 18 to control the surge absorption process of the resistive absorption circuit 16, and adopts the unidirectional conductive element (diode) to control the surge absorption process of the capacitive absorption circuit.

[0097] In another embodiment of the present invention, Figure 6 、 Figure 7 As shown, the drive control circuit uses the resistive absorption circuit 16 alone. In comparison, Figure 5 The drive control circuit shown has a better effect of absorbing surge energy and a more stable bus voltage.

[0098] In any of the above embodiments, preferably, the selection of the carrier frequency and the duty cycle is related to the first preset threshold, the resistance value, the rated power and the instantaneous overload capacity of the first resistive element 28 .

[0099] In another embodiment of the present invention, preferably, the drive control circuit also includes a rectifier circuit 42, which rectifies the AC signal and outputs it as a bus signal. The bus signal is output to the bus capacitor 14, the inverter bridge 10 and the load through the high-voltage bus and the low-voltage bus, wherein the control chip controls the conduction state of the switching element 18 according to the AC signal.

[0100] In this embodiment, the AC signal is processed into a bus signal by the rectifier circuit 42 , and both the bus signal and the AC signal can be used as determination conditions for controlling the switching element 18 to be turned on or off.

[0101] Specifically, the bus signal can be obtained by detecting the voltage before the reactor 12 after the rectifier circuit 42 and / or the voltage before the inverter bridge 10 after the reactor 12; the AC signal is the peak value signal of the AC input voltage and / or the voltage signal before the rectifier circuit 42.

[0102] In any of the above embodiments, preferably, the control chip controls the conduction state of the switching element 18 according to the AC signal specifically as follows: comparing the voltage value corresponding to the AC signal collected in real time with a preset fifth threshold, determining that the voltage value is greater than or equal to the fifth threshold, then controlling the switching element 18 to conduct; comparing the voltage value corresponding to the AC signal with a preset sixth threshold, determining that the voltage value is less than or equal to the sixth threshold, then controlling the switching element 18 to cut off. Among them, the fifth threshold and the sixth threshold are the conduction threshold and the cut-off threshold of the switching element 18 preset according to the AC signal. In addition, for the comparison circuit 20, the conduction threshold (seventh threshold) and the cut-off threshold (eighth threshold) of the switching element 18 can also be preset according to the AC signal. The seventh threshold is greater than the eighth threshold, the eighth threshold is greater than the fifth threshold, and the fifth threshold is greater than the sixth threshold.

[0103] In any of the above embodiments, preferably, the bus capacitor 14 is a thin film capacitor.

[0104] In any of the above embodiments, the capacitance value of the bus capacitor 14 is less than a preset capacity, and the preset capacity is calculated according to the following calculation formula:

[0105]

[0106] Where C dc is the preset capacity, L S is the total inductance value on the DC side of the equivalent drive control circuit, P L is the load power of the drive control circuit, R S is the total resistance on the DC side of the equivalent drive control circuit, v dc0 is the average value of the bus voltage. For example, taking the 7P prototype as an example, according to this calculation formula, C dc must be greater than 840 uF, the preset capacity is above 840 uF, and 1230 uF is used in the specific implementation.

[0107] To better illustrate the present invention, the actual operation setting parameters of the 6KW prototype are as follows:

[0108] The reactor Lac refers to the actual AC side inductor model and the input power line inductor, which includes the inductance and resistance. The existing model uses an AC side inductor of 25 mH and 500 mΩ, and the inductance of the input power line is less than or equal to 10 mH (numerical amplification), and the resistance is not less than 0.5 Ω (the actual wire resistance used is about 1.2 Ω);

[0109] The reactor 12 refers to the actual DC-side inductance model, which includes inductance and resistance, 4.5 mH and 120 mΩ.

[0110] R4 is the system damping resistor (not greater than 200 Ω, 68 Ω is used on the 16KW prototype, and it can actually be not used). When the reactor 12 selects 4.5 mH, the damping resistor R4 is not added. On the 6KW prototype, R4 can also be absent without the reactor 12.

[0111] It should be noted that: Lac and the reactor 12 exist for EMC harmonic requirements. In areas with harmonic requirements, Lac may exist on the prototype, the reactor 12 may exist, or even Lac and the reactor 12 may coexist. For areas without harmonic requirements, neither Lac nor the reactor 12 exists. However, for high-frequency harmonic problems (if this problem is ignored, the reactor 12 can be not used), a smaller reactor Ldc will be used at the position of the reactor 12 in the circuit topology. A small damping resistor is connected in parallel to this smaller Ldc to improve system stability.

[0112] The discharging element 30 is an antiparallel diode. The selection of this diode is related to the inductance and resistance value of the first resistive element 28. If the first resistive element 28 is a non-inductive resistor, the discharging element 30 can be not used. Currently, on the 6KW prototype, the first resistive element 28 used is composed of 4 absorption resistors with specifications of A watts and B ohms in series.

[0113] Regarding the limit calculation of the continuous conduction time of the absorption resistor: Assume that the software is set to conduct at 720V and the hardware is set to conduct at 800V. Due to reasons such as detection and filtering, the actual conduction voltage is at most 800V. Since the four absorption resistors are in series, the maximum voltage on each absorption resistor is 200V. Then (200×200÷B)÷t = A, from which t can be calculated. That is to say, the continuous conduction time within 1 second should not exceed t.

[0114] Operation instructions:

[0115] When the prototype is powered on, the input voltage is rectified by the rectifying circuit 42 and simultaneously charges the bus capacitor 14 and the first capacitive element 32 and the second capacitive element 36 in the capacitive absorption circuit 24. At this time, if the input voltage is within the normal set range (150V - 264V) and does not exceed 294V, the hardware protection voltage threshold is set to 800V and the software protection threshold is set to 720V. The corresponding AC input effective value is 720÷1.414÷1.732 = 294V. The prototype operates normally and the switching element 18 is not conducting. After the charging is completed, the voltage across the absorption resistor stabilizes at the Vdc-max value (changing slowly).

[0116] When the prototype operates normally, the voltage on the bus capacitor 14 fluctuates at a frequency six times that of the AC input power supply frequency. When operating normally, the maximum value of the bus voltage is 264×1.414×1.732 = 646V, which is much less than the set protection threshold. Therefore, the switching element 18 will not function.

[0117] The surge energy mainly comes from the power input, the compressor winding when the prototype fails and stops, the freewheeling of the AC-DC side inductors, and the kinetic energy of the compressor. When a surge comes, since the bus capacitor 14 (film capacitor or small-capacity electrolytic capacitor) has limited ability to absorb the surge, the bus voltage will rise rapidly.

[0118] Note: Currently, there are a total of four threshold voltages, two of which are software-based and two are hardware-based. The two software-based ones are: the first preset threshold V2 and the second preset threshold V1. The two hardware-based ones are: the third preset threshold V3 and the fourth preset threshold V4, where V3 > V4 > V2 > V1. For different corresponding states, when the first preset threshold V2 is triggered, the software will output a PWM control switch device regardless of whether there is a comparator interrupt signal. When the second preset threshold V1 is triggered, the software turns off the PWM output. When the hardware's third preset threshold V4 is triggered, the control chip will receive the interrupt signal generated by the comparator and output a PWM signal. When the fourth preset threshold V4 is triggered, the PWM output is turned off.

[0119] The DC bus voltage passes through the voltage-dividing resistors R5 and R6, and the divided bus voltage enters the AD sampling port of the control chip 22 and the input end of the comparison circuit 20. When the divided bus voltage is greater than the set threshold of the comparison circuit 20, the output of the comparison circuit 20 changes from the second level to the first level, and the level change signal enters the external interrupt port of the control chip 22. When the control chip 22 receives the external interrupt signal, it is judged that the current bus voltage exceeds 800V. At this time, the control chip 22 controls the motor to start running at a reduced frequency, and at the same time outputs a PWM switch signal to the switching element 18 in the form of a fixed carrier frequency (such as 40K) and a fixed duty cycle (such as 50%). Due to the intervention of the absorption resistor, the bus voltage will drop rapidly. When it is lower than the second preset threshold V1, the control chip 22 turns off the PWM switch signal output, the switching element 18 disconnects, and the absorption resistor no longer functions. The surge process is as Figure 8 shown.

[0120] In addition, in order to protect the absorption resistor, the sum of the continuous conduction times within 1s is limited. When the first preset threshold V2 is 720V, due to reasons such as software detection delay, the hardware will start to act at a maximum of 800V. Then, for four absorption resistors in series with A watts and B ohms, the continuous conduction time limit within 1s is t1. If t is 1.25ms, then t1 is 1ms.

[0121] It should be noted that the selection of the carrier frequency and the duty cycle is mainly determined by the set first preset threshold V2, the resistance value of the absorption resistor, the rated power of the absorption resistor, and the instantaneous overload capacity; generally speaking, the greater the rated power of the absorption resistor, the greater its instantaneous overload capacity. Therefore, under the same action threshold V2, the greater the duty cycle that can be turned on or the smaller the carrier frequency (i.e., the larger the period). For example, for a 16KW prototype, when V2 is 800V, two 20W 10-ohm resistors are connected in series as the absorption resistor, and the conduction time is 1.5ms.

[0122] In addition, various fixed duty cycle forms can be combined. For example, in one or more initial conduction cycles, the PWM duty cycle is 70%; in the subsequent multiple cycles, it is turned on in the form of 50% (which can be other duty cycle values).

[0123] Regarding the first preset threshold V2 and the second preset threshold V1, they are set to fixed values of 720V and 700V here, and they can be floating values (such as detecting the Vdc-max value in the previous few detection cycles (such as 100ms), and using Vdc-max + △V as the turn-off voltage threshold of the switching element 18 (i.e., the second preset threshold V1), and using Vdc-max + △V + 20V (which can be other values) as the turn-on voltage threshold of the switching element 18 (the first preset threshold V2). Of course, it can also be extended to detect the peak value of the AC input, using the AC input peak value Vac-max + △V as the second preset threshold V1, and using Vdc-max + △V1 + 20V (which can be other values) as the first preset threshold V2.

[0124] In addition, regarding the judgment of overvoltage and the exit from overvoltage, in the present invention, a hardware comparator is used to compare with a set threshold to generate a level conversion to determine overvoltage, and software is used to detect in real time that the bus voltage is lower than a certain value to be set as the exit from overvoltage; preferably, it can be extended to both overvoltage and the exit from overvoltage are given by a hardware hysteresis comparator.

[0125] Another aspect of the present invention provides an air conditioner, including: a motor; a drive control circuit as described in any one of the above embodiments, the signal input end of the motor is connected to the drive control circuit, and the drive signal output by the drive control circuit is used to drive the motor to operate.

[0126] The air conditioner provided by the embodiment of the present invention includes the drive control circuit as described in any one of the above embodiments, and thus has all the technical effects of the drive control circuit, which will not be elaborated here.

[0127] In the description of this specification, the terms "first" and "second" are used for descriptive purposes only and cannot be construed as indicating or implying relative importance unless otherwise clearly specified and defined; the terms "connection", "installation", "fixation", etc. should all be understood in a broad sense. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0128] In the description of this specification, the description of terms such as "one embodiment", "some embodiments", "specific embodiments", etc. means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or instance. Moreover, the specific features, structures, materials or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0129] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A drive control circuit, comprising: An inverter bridge is used to drive and control the operation of a load. The inverter bridge is connected between a high-voltage bus and a low-voltage bus. It is characterized in that the drive control circuit further includes: a reactor for absorbing surge signals generated during the process of the drive control circuit driving the load to operate. The reactor is connected between the power grid and the load; a bus capacitor for providing the starting voltage required for the load to be powered on, and the bus capacitor is also used to absorb the surge signals. The bus capacitor is connected to the bus line on the input side of the inverter bridge; a sampling circuit for sampling the bus signal to determine the bus voltage; and the drive control circuit further includes: A resistive absorption circuit for absorbing the surge signals on the bus line. The resistive absorption circuit is connected in parallel with the bus capacitor; A switching element for regulating the process of the resistive absorption circuit absorbing the surge signals. The switching element is connected in series with the resistive absorption circuit; A control chip for determining whether to output a preset pulse width modulation signal to the switching element according to the magnitude relationship between the bus voltage and a preset threshold. The control chip is respectively connected to the switching element and the sampling circuit; The resistive absorption circuit includes: A first resistive element for absorbing the surge signals. The first resistive element is connected in series with the switching element; The switching element is specifically used to control the process of the first resistive element absorbing the surge signals; A discharge element for releasing the peak voltage of the first resistive element. The discharge element is connected in parallel with the first resistive element; The discharge element is a diode, or a series combination of a diode and a resistor, or the discharge element includes a series-connected resistor and capacitor; The bus capacitor is a thin-film capacitor, and the capacitance value of the bus capacitor is less than a preset capacitance. The preset capacitance is calculated according to the following calculation formula: ， Among them, is the preset capacity, is the total inductance value on the DC side of the equivalent drive control circuit, is the load power of the drive control circuit, is the total resistance on the DC side of the equivalent drive control circuit, is the average value of the bus voltage; The control chip is specifically used for: Based on the condition that the bus voltage is greater than or equal to a first preset threshold, output the preset pulse width modulation signal to the switching element; Based on the condition that the bus voltage is less than a second preset threshold, stop outputting the preset pulse width modulation signal; Wherein, the first preset threshold is greater than the second preset threshold; The first preset threshold and the second preset threshold are bus voltage protection thresholds, and the first preset threshold and the second preset threshold respectively correspond to the conduction threshold and the turn-off threshold of the switching element; The drive control circuit has a capacitive absorption circuit for absorbing the surge signals on the bus line. The capacitive absorption circuit is connected in parallel with the bus capacitor; The capacitive absorption circuit includes: A first capacitive element for absorbing the surge signals on the bus line. The first capacitive element is connected in series with a unidirectional conduction element; A second resistive element for releasing the surge signals in the first capacitive element. The second resistive element is connected in parallel with the first capacitive element; [[ID= 2. The drive control circuit according to claim 1, wherein ​ The unidirectional conduction element is used to regulate the process of the capacitive absorption circuit absorbing the surge signal, and the unidirectional conduction element is connected in series with the capacitive absorption circuit.

3. The drive control circuit according to claim 2, characterized in that, The capacitive absorption circuit includes: A second capacitive element for absorbing the surge signal on the bus line, and the second capacitive element is connected in series with the first capacitive element; A third resistive element for releasing the surge signal in the second capacitive element, and the third resistive element is connected in parallel with the second capacitive element.

4. The drive control circuit according to claim 3, wherein It further includes: A fourth resistive element for limiting the current flowing through the capacitive absorption circuit, and the fourth resistive element is connected in series in the branch where the capacitive absorption circuit and the unidirectional conduction element are located.

5. The drive control circuit according to claim 1, characterized in that, The drive control circuit further includes: A rectifier circuit that rectifies the AC signal and outputs it as the bus signal, and the bus signal is output to the bus capacitor, the inverter bridge, and the load through the high-voltage bus and the low-voltage bus, wherein, the control chip controls the conduction state of the switching element according to the AC signal.

6. The drive control circuit according to claim 1, wherein It further includes: A comparison circuit for outputting a corresponding level signal to the control chip according to the bus voltage, the input end of the comparison circuit is connected to the output end of the sampling circuit, and the output end of the comparison circuit is connected to the control chip; The control chip is further used to determine whether to output the preset pulse width modulation signal to the switching element according to the level signal.

7. The drive control circuit according to claim 6, wherein the comparison circuit is specifically configured to: output a first level signal based on the condition that the bus voltage is greater than or equal to a third preset threshold; and output a second level signal based on the condition that the bus voltage is less than or equal to a fourth preset threshold; the control chip is specifically configured to: output the preset pulse width modulation signal to the switching element when receiving the first level signal or a flip signal that changes from the second level signal to the first level signal; the third preset threshold is greater than the fourth preset threshold, and the fourth preset threshold is greater than the first preset threshold.

8. An air conditioner, characterized in that, The air conditioner includes: A motor; [[ID=

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