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 first resistive element, a switching element, and a current measuring element. The switching element is configured to control the first resistive element to absorb the surge signal on the high-voltage bus. The current measuring element is used to measure the current signal flowing through the first resistive element. The first resistive element, the switching element, and the current measuring element are connected in series between the high-voltage bus and the low-voltage bus. A control chip is used to detect and confirm that the current signal is greater than a preset current threshold, and stop driving the switching element, so that the first resistive element stops absorbing the surge signal, reducing the possibility of components in the drive control circuit being damaged due to overcurrent.

Description

[0001] This application claims the priority of the Chinese patent application filed with the China Patent Office on January 16, 2019, with application number 201910041269.7 and invention name “Drive Control Circuit and Air Conditioner”, the entire contents of which are incorporated by reference in this application. Technical Field

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

[0003] For example, three-phase load devices such as compressors, motors, and engines use an AC-DC-AC topology. Specifically, the AC-DC-AC topology is Figure 1 As shown, it includes: an AC power supply module, a power filter module, a rectifier module, a filter module, an inverter module and a load.

[0004] Since the filter module needs to smooth the rectified power frequency signal, a large-capacity electrolytic capacitor is often used as the main filter element. However, the use of electrolytic capacitors will increase the THD (Total Harmonic Distortion) of the input AC current, and its short lifespan affects the lifespan of the controller. In addition, the heat generated by the electrolytic capacitor reduces the efficiency of the controller.

[0005] As the cost and reliability requirements increase, the electrolytic capacitor capacity is reduced and even the electrolytic capacitor-free control solution is gradually mature. For the electrolytic capacitor-free control solution, a smaller film capacitor is generally used to replace the electrolytic capacitor. Due to the reduction in busbar capacitance, the surge absorption capacity becomes worse, and its defects are mainly reflected in the following two aspects:

[0006] 1. Film capacitors or smaller electrolytic capacitors have limited surge absorption, resulting in excessive bus voltage and damage to components.

[0007] 2. Film capacitors or smaller electrolytic capacitors have limited surge absorption. If a surge voltage is input during normal operation of the prototype, the bus voltage will change dramatically in an instant, affecting control stability. Summary of the invention

[0008] The present invention aims to solve at least one of the technical problems existing in the prior art or related art.

[0009] To this end, a first aspect of the present invention is to provide a drive control circuit.

[0010] A second aspect of the present invention is to provide an air conditioner.

[0011] In view of this, according to the first aspect of the present invention, a drive control circuit is provided, including: an inverter bridge, which drives and controls a load to operate, so as to drive a motor to operate, and the inverter bridge is connected between a high-voltage bus and a low-voltage bus; a bus capacitor, which is used to provide a starting voltage required for the load to be powered on, and the bus capacitor is also used to absorb surge signals, and the bus capacitor is connected to the bus line on the input side of the inverter bridge; a reactor, which is used to absorb the surge signals generated during the operation of the drive control circuit driving the load, and the reactor is connected between the power grid and the load; a sampling circuit, which is used to collect the voltage signal of the high-voltage bus, and further includes: a first resistive element, a switching element, and a current measuring element, the switching element is configured to control the first resistive element to absorb the surge signal on the high-voltage bus, the current measuring element is used to measure the current signal flowing through the first resistive element, and the first resistive element, the switching element, and the current measuring element are connected in series between the high-voltage bus and the low-voltage bus; a control chip, which is used to detect and confirm that the current signal is greater than a preset current threshold, and stop driving the switching element, so that the first resistive element stops absorbing the surge signal.

[0012] The drive control circuit according to the embodiment of the present invention is for a motor driven by an inverter bridge. Among them, the drive control circuit includes: an inverter bridge, a bus capacitor, a reactor, a control chip, and a first resistive element, a switching element, and a current measuring element. The inverter bridge outputs a drive signal to the motor to control the operation of the motor. Since the surge signal formed on the high-voltage bus cannot be ensured to be completely absorbed, a first resistive element and a switching element are connected in series between the high-voltage bus and the low-voltage bus, and a current measuring element for sampling the current in the circuit of the first resistive element and the switching element is provided. When the current signal flowing through the first resistive element is greater than or equal to a preset current threshold, the control chip stops driving the switching element, so that the first resistive element stops absorbing the surge signal, and on the premise of increasing the surge absorption capacity of the drive control circuit, the possibility of the components in the drive control circuit being damaged due to overcurrent is reduced.

[0013] The drive control circuit according to the above embodiment of the present invention may further have the following technical features:

[0014] In any of the above technical solutions, further, the control chip is further used for: detecting and confirming that the absorption power of the first resistive element is greater than a preset power threshold, and stopping driving the switching element, so that the first resistive element stops absorbing the surge signal.

[0015] In this technical solution, by comparing the absorption power of the first resistive element with a preset power threshold, when the absorption power is greater than the preset power threshold, the driving of the switching element is stopped, and the possibility of the components in the drive control circuit being damaged due to excessive absorption power is reduced.

[0016] In any of the above technical solutions, further, the control chip is further configured to: detect and confirm that the voltage signal of the high-voltage bus is less than a first preset threshold, and stop driving the switching element so that the first resistive element stops absorbing the surge signal; and detect and confirm that the voltage signal of the high-voltage bus is greater than or equal to a second preset threshold, and control the switching element to operate according to a preset specified carrier frequency or a preset specified conduction time or a preset specified duty ratio, so that the first resistive element absorbs the surge signal.

[0017] Optionally, the specified carrier frequency, the specified conduction time, and the specified duty ratio are all the maximum values.

[0018] In this technical solution, through the step of comparing the first preset threshold with the voltage signal of the high-voltage bus, when the voltage signal is less than the first preset threshold, the driving of the switching element is stopped, thereby avoiding the connection of the first resistive element to the high-voltage bus within the normal voltage input range, prolonging the service life of the first resistive element. Conversely, the switching element is controlled to operate according to a preset minimum carrier frequency (fixed duty ratio) or a preset maximum conduction time or a preset maximum duty ratio (fixed carrier frequency), thereby achieving rapid absorption of the surge signal. Among them, the first preset threshold is less than the second preset threshold.

[0019] In any of the above technical solutions, further, the drive control circuit further includes: a first capacitive element, and the first capacitive element is used to absorb the surge signal on the high-voltage bus. The first capacitive element is connected in series between the high-voltage bus and the low-voltage bus.

[0020] In this technical solution, by connecting a capacitive element in series between the high-voltage bus and the low-voltage bus, the additional capacitive element is used to absorb the surge signal on the high-voltage bus, thereby improving the surge absorption ability of the drive control circuit, reducing the damage of components in the drive control circuit caused by the surge signal, and improving the reliability of the circuit.

[0021] In any of the above technical solutions, further, the drive control circuit further includes: a unidirectional conduction element, and the unidirectional conduction element is configured to control the first capacitive element to absorb the surge signal on the high-voltage bus. The first capacitive element is connected in series with the unidirectional conduction element; or the unidirectional conduction element is configured to control the first capacitive element and / or the first resistive element to absorb the surge signal on the high-voltage bus. The unidirectional conduction element is connected in series with the first capacitive element, and the first resistive element, the switching element, and the current measuring element are connected to the high-voltage bus through the unidirectional conduction element.

[0022] In this technical solution, by providing a unidirectional conduction element, only when the unidirectional conduction element meets the conduction condition, can the first capacitive element and / or the first resistive element absorb the surge signal on the high-voltage bus, preventing the first capacitive element from being used as a bus capacitor, thereby increasing the service life of the first capacitive element. Similarly, the service life of the first resistive element is also increased, thus enhancing the surge absorption ability of the drive control circuit. Herein, the unidirectional conduction element is an element with unidirectional conduction characteristics, such as a diode, etc.

[0023] In any of the above technical solutions, further, the drive control circuit further includes: a second resistive element, which is used to release the surge signal in the first capacitive element, and the second resistive element is connected in parallel with the first capacitive element.

[0024] In this technical solution, after the first capacitive element absorbs the surge signal on the high-voltage bus, the second resistive element connected in parallel with the first capacitive element is used to release the surge signal in the first capacitive element. The provision of the second resistive element improves the reliability of the drive control circuit.

[0025] A comparison circuit, which is used to detect and confirm that the voltage signal of the high-voltage bus is greater than or equal to or greater than a third preset threshold. The comparator output level flip signal can trigger the port of the control chip. The control chip can switch the switch control signal according to the comparator output signal to change the absorption of surge energy by the first resistive element. The comparison circuit is respectively connected to the sampling circuit and the control chip.

[0026] In any of the above technical solutions, further, the drive control circuit further includes: a comparison circuit, which is used to detect and confirm that the voltage signal of the high-voltage bus is greater than or equal to a third preset threshold. The comparison circuit output level flip signal can trigger the port of the control chip. The control chip switches the control signal of the switching element according to the level flip signal to change the absorption of surge energy by the first resistive element. The comparison circuit is respectively connected to the sampling circuit and the control chip.

[0027] In this technical solution, by providing a comparison circuit, when the voltage signal of the high-voltage bus is greater than or equal to or greater than the third preset threshold, the comparator output level flip signal triggers the port of the control chip. The control chip can switch the switch control signal according to the comparator output signal to change the absorption of surge energy by the first resistive element; when the voltage signal of the high-voltage bus is less than the fourth preset threshold, triggering the port of the control chip is stopped, and the absorption of the surge signal by the first resistive element is stopped. Preferably, the comparison circuit triggering the interrupt port of the control chip belongs to hardware triggering. Compared with software triggering, the response speed is fast, thereby reducing the possibility of the drive control circuit malfunctioning. Herein, the third preset threshold is greater than the fourth preset threshold.

[0028] Optionally, the comparison circuit is further configured to detect and confirm that when the voltage signal of the high-voltage bus is greater than or equal to a fourth preset threshold, the comparison circuit outputs a level inversion signal to the control chip, and the control chip switches the control signal of the switching element, where the fourth preset threshold is less than the third preset threshold and greater than the first preset threshold.

[0029] In any of the above technical solutions, further, it further includes: a second capacitive element, configured to absorb the surge signal on the high-voltage bus, and the second capacitive element is connected in series with the first capacitive element.

[0030] In this technical solution, in order to adapt to the high-voltage bus, when the voltage of the high-voltage bus is relatively large, a second capacitive element is connected in series on the basis of the first capacitive element to improve the absorption ability of the surge signal on the high-voltage bus.

[0031] In any of the above technical solutions, further, it further includes: a third resistive element, and the third resistive element is configured to release the surge signal in the second capacitive element, and the third resistive element is connected in parallel with the second capacitive element.

[0032] In this technical solution, in the case of setting the second capacitive element, by setting the third resistive element to cooperate with the second resistive element, the voltage across the first capacitive element and the second capacitive element is balanced, and at the same time, the third resistive element is also configured to release the surge signal on the second capacitive element, thereby improving the reliability of the drive control circuit.

[0033] In any of the above technical solutions, further, a fourth resistive element is configured to limit the current flowing through at least one of the first capacitive element, the second capacitive element, and / or the first resistive element; the fourth resistive element, the first capacitive element, and the unidirectional conduction element are connected in series and then connected between the high-voltage bus and the low-voltage bus; or the fourth resistive element, the first capacitive element, the second capacitive element, and the unidirectional conduction element are connected in series and then connected between the high-voltage bus and the low-voltage bus; or the unidirectional conduction element is connected in series with the fourth resistive element and then connected between the high-voltage bus and the low-voltage bus through the first capacitive element and / or the second capacitive element and through the first resistive element, the switching element, and the current measuring element.

[0034] In this technical solution, the setting of the fourth resistive element limits the current flowing through the circuit where it is located, avoids the situation of excessive instantaneous current, thereby causing component damage, improves the reliability of the drive control circuit, and at the same time, the fourth resistive element also plays a role in absorbing the surge signal in the circuit where it is located, thereby improving the absorption ability of the surge signal of the drive control circuit.

[0035] In any of the above technical solutions, further, the current measuring element is a Hall sensor or a resistive element.

[0036] In this technical solution, the manufacturing process of the Hall sensor is mature and the cost is low.

[0037] In any of the above technical solutions, further, the bus capacitor is a thin-film capacitor.

[0038] In any of the above technical solutions, further, it further includes: a rectifying circuit, which rectifies the AC signal and outputs it as the voltage signal of the high-voltage bus.

[0039] According to the second aspect of the present invention, an air conditioner is provided, including: a motor; and a drive control circuit as described in any of the above technical solutions, wherein 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. Therefore, the air conditioner has all the beneficial effects of the drive control circuit described in any of the above embodiments, which will not be elaborated herein.

[0040] The additional aspects and advantages of the present invention will become apparent in the following description section or be understood through the practice of the present invention. Description of the Drawings

[0041] The above and / or additional aspects and advantages of the present invention will become apparent and be readily understood from the description of the embodiments in conjunction with the following drawings, wherein:

[0042] Figure 1 Shows the AC-DC-AC topology in the prior art;

[0043] Figure 2 Shows a schematic diagram of a drive control circuit;

[0044] Figure 3 Shows a schematic diagram of the drive control circuit of an embodiment of the present invention;

[0045] Figure 4 Shows a schematic diagram of the drive control circuit of another embodiment of the present invention;

[0046] Figure 5 Shows a schematic diagram of the drive control circuit of still another embodiment of the present invention;

[0047] Figure 6 Shows a schematic diagram of the drive control circuit of yet another embodiment of the present invention;

[0048] Figure 7 Shows a schematic diagram of the drive control circuit of yet another embodiment of the present invention;

[0049] Figure 8 Shows a schematic diagram of the drive control circuit of yet another embodiment of the present invention;

[0050] Figure 9 Shows a schematic diagram of the drive control circuit of yet another embodiment of the present invention;

[0051] Figure 10 Schematic diagram of a drive control circuit showing another embodiment of the present invention;

[0052] Figure 11 Schematic diagram of a drive control circuit showing another embodiment of the present invention;

[0053] Figure 12 Schematic diagram of a drive control circuit showing another embodiment of the present invention;

[0054] Figure 13 Schematic diagram of a drive control circuit showing another embodiment of the present invention;

[0055] Figure 14 Schematic diagram of surge signal absorption showing an embodiment of the present invention;

[0056] Figure 15 Schematic diagram of sampling showing an embodiment of the present invention;

[0057] Figure 16 Schematic diagram of surge signal absorption showing another embodiment of the present invention;

[0058] Figure 17 Schematic diagram of sampling showing another embodiment of the present invention;

[0059] Figure 18 Schematic diagram of control showing an embodiment of the present invention;

[0060] Figure 19 Schematic diagram showing the relationship between instantaneous absorption power and duration in the embodiments of the present invention.

[0061] Wherein, Figures 2 to 13 The corresponding relationship between the reference numerals and the component names in

[0062] 102 Inverter bridge, 104 Switch element, 106 Comparison circuit, 108 Control chip, 110 Discharge element, 112 Current measuring element, 114 Rectifier circuit. Detailed implementation manners

[0063] In order to more clearly understand the above aspects, 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 may be combined with each other.

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

[0065] An embodiment of the first aspect of the present invention provides a drive control circuit. As Figure 2 shown, the drive control circuit includes: an inverter bridge 102, which drives and controls a load to operate, so as to drive a motor to operate. The inverter bridge 102 is connected between a high-voltage bus and a low-voltage bus; a bus capacitor C1, which is used to provide the starting voltage required for the load to be powered on, and is also used to absorb surge signals. The bus capacitor C1 is connected to the bus line on the input side of the inverter bridge 102; a reactor Ldc, which is used to absorb the surge signals generated during the operation of the drive control circuit driving the load. The reactor Ldc is connected between the power grid and the load; a sampling circuit, which is used to collect the voltage signal of the high-voltage bus; a first resistive element R1, a switching element 104, and a current measuring element 112. The switching element 104 is configured to control the first resistive element R1 to absorb the surge signals on the high-voltage bus. The current measuring element 112 is used to measure the current signal flowing through the first resistive element R1. The first resistive element R1, the switching element 104, and the current measuring element 112 are connected in series between the high-voltage bus and the low-voltage bus; a control chip 108, which is used to stop driving the switching element 104 when it detects and confirms that the current signal is greater than a preset current threshold, so that the first resistive element R1 stops absorbing the surge signals.

[0066] The drive control circuit according to the embodiment of the present invention is for a motor driven by an inverter bridge. Among them, the drive control circuit includes: an inverter bridge 102, a bus capacitor C1, a reactor Ldc, a control chip 108, and a first resistive element R1, a switching element 104, and a current measuring element 112. Among them, the inverter bridge 102 outputs a drive signal to the motor to control the operation of the motor. Since the surge signals formed on the high-voltage bus cannot be ensured to be completely absorbed, a first resistive element R1 and a switching element 104 are connected in series between the high-voltage bus and the low-voltage bus. At the same time, a current measuring element 112 for determining and sampling the current in the first resistive element R1 and the switching element 104 is provided. When the current signal flowing through the first resistive element R1 is greater than or equal to the preset current threshold, the control chip stops driving the switching element 104, so that the first resistive element R1 stops absorbing the surge signals, and on the premise of increasing the surge absorption capacity of the drive control circuit, the possibility of components in the drive control circuit being damaged due to overcurrent is reduced.

[0067] Among them, the preset current threshold is related to the current limiting current of the switching element 104 and / or the rated power of the first resistive element R1.

[0068] In one embodiment of the present invention, as Figure 12 shown, the control chip 108 is further configured to: detect and confirm that the absorption power of the first resistive element R1 is greater than a preset power threshold, and stop driving the switching element 104, so that the first resistive element R1 stops absorbing the surge signal.

[0069] In this embodiment, by comparing the absorption power of the first resistive element R1 with the preset power threshold, when the absorption power is greater than the preset power threshold, the driving of the switching element 104 is stopped, avoiding damage to the components due to excessive absorption power. Among them, the absorbed absorption power is calculated in real time through the voltage value of the bus and the resistance value of the first resistive element, that is, Vdc×Vdc / R, where Vdc is the bus voltage and R is the resistance value of the first resistive element R1.

[0070] In one embodiment of the present invention, as Figure 2 shown, the control chip 108 is further configured to: detect and confirm that the voltage signal of the high-voltage bus is less than a first preset threshold, stop driving the switching element 104, so that the first resistive element R1 stops absorbing the surge signal; and detect and confirm that the voltage signal of the high-voltage bus is greater than or equal to a second preset threshold, and control the switching element 104 to operate according to a preset specified carrier frequency (fixed duty cycle) or a preset specified conduction time or a preset specified duty cycle (fixed carrier frequency), so that the first resistive element R1 absorbs the surge signal.

[0071] Optionally, the specified carrier frequency, the specified conduction time, and the specified duty cycle are all the maximum values.

[0072] In this embodiment, through the step of comparing the first preset threshold with the voltage signal of the high-voltage bus, when the voltage signal is less than the first preset threshold, the driving of the switching element 104 is stopped, thereby avoiding the first resistive element R1 from being connected to the high-voltage bus within the normal voltage input range and extending the life of the first resistive element R1. On the contrary, the switching element 104 is controlled to operate according to a preset minimum carrier frequency (fixed duty cycle) or a preset maximum conduction time or a preset maximum duty cycle (fixed carrier frequency), thereby realizing the rapid absorption of the surge signal. Among them, the first preset threshold is less than the second preset threshold.

[0073] Among them, the first preset threshold and the second preset threshold are related to the voltage of the high-voltage bus.

[0074] In one embodiment of the present invention, as Figures 2 to 9 shown, the drive control circuit further includes: a first capacitive element C2, and the first capacitive element C2 is used to absorb the surge signal on the high-voltage bus. The first capacitive element C2 is connected in series between the high-voltage bus and the low-voltage bus.

[0075] In this embodiment, by connecting a capacitive element in series between the high-voltage bus and the low-voltage bus, the additionally provided capacitive element is used to absorb the surge signal on the high-voltage bus, thereby improving the surge absorption ability of the drive control circuit, reducing the damage of components in the drive control circuit caused by the surge signal, and improving the reliability of the circuit.

[0076] In an embodiment of the present invention, as Figures 2 to 9 shown, the drive control circuit further includes:

[0077] A unidirectional conduction element D1, the unidirectional conduction element D1 is configured to limit the first capacitive element C2 from absorbing the surge signal on the high-voltage bus, and the first capacitive element C2 is connected in series with the unidirectional conduction element D1; or the unidirectional conduction element D1 is configured to control the first capacitive element C2 and / or the first resistive element R1 to absorb the surge signal on the high-voltage bus, the unidirectional conduction element D1 is connected in series with the first capacitive element C2, and the first resistive element R1, the switching element 104, and the current measuring element 112 are connected to the high-voltage bus through the unidirectional conduction element D1.

[0078] In this embodiment, by setting the unidirectional conduction element, only when the unidirectional conduction element D1 meets the conduction condition, can the surge signal on the high-voltage bus be absorbed through the first capacitive element C2 and / or the first resistive element R1, avoiding the first capacitive element C2 being used as a bus capacitor, thereby improving the service life of the first capacitive element C2. Similarly, the service life of the first resistive element R1 is also improved, thereby improving the surge absorption ability of the drive control circuit. Specifically, the anode of the unidirectional conduction element D1 is connected to the high-voltage bus, and the cathode of the unidirectional conduction element D1 is connected to the low-voltage bus via the first capacitive element C2, where the unidirectional conduction element D1 is an element with unidirectional conduction characteristics, such as a diode, etc.

[0079] In an embodiment of the present invention, as Figures 2 to 9 shown, the drive control circuit further includes: a second resistive element R2, the second resistive element R2 is used to release the surge signal in the first capacitive element C2, and the second resistive element R2 is connected in parallel with the first capacitive element C2.

[0080] In this embodiment, after the first capacitive element C2 absorbs the surge signal on the high-voltage bus, the second resistive element R2 provided in parallel with the first capacitive element C2 is used to release the surge signal in the first capacitive element C2, and the setting of the second resistive element R2 improves the reliability of the drive control circuit.

[0081] In an embodiment of the present invention, further, as Figure 2As shown, the drive control circuit further includes: a comparison circuit 106 for detecting and confirming that the voltage signal of the high-voltage bus is greater than or equal to a third preset threshold. The comparison circuit 106 outputs a level inversion signal to trigger the port of the control chip 108. The control chip 108 switches the control signal of the switching element 104 according to the level inversion signal to change the absorption of surge energy by the first resistive element R1, so as to reduce the output power of the high-voltage bus. The comparison circuit is respectively connected to the sampling circuit and the control chip 108.

[0082] In this embodiment, by setting the comparison circuit 106, when the voltage signal of the high-voltage bus is greater than or equal to the third preset threshold, the comparison circuit 106 outputs a level inversion signal to trigger the port of the control chip 108. The control chip 108 switches the control signal of the switching element 104 according to the level inversion signal to change the absorption of surge energy by the first resistive element R1, so as to reduce the output power of the high-voltage bus, and reduce the surge signal by reducing the output power of the bus; when the voltage signal of the high-voltage bus is less than or less than equal to the fourth preset threshold, the interruption port of the control chip is stopped from being triggered, and the absorption of the surge signal by the first resistive element is stopped. Preferably, the comparison circuit triggering the interruption port of the control chip belongs to hardware triggering, which has a faster response speed compared with software triggering, thereby reducing the possibility of the drive control circuit malfunctioning. Among them, the third preset threshold is greater than the fourth preset threshold. Further, the fourth preset threshold is greater than the first preset threshold. The third preset threshold is related to the voltage of the high-voltage bus, and the fourth preset threshold is related to the voltage of the high-voltage bus.

[0083] Optionally, the comparison circuit 106 is further used for detecting and confirming that when the voltage signal of the high-voltage bus is greater than or equal to the fourth preset threshold, the comparison circuit 106 outputs a level inversion signal to the control chip 108, and the control chip 108 switches the control signal of the switching element 104, where the fourth preset threshold is less than the third preset threshold and greater than the first preset threshold.

[0084] In an embodiment of the present invention, further, as Figures 2 to 9 shown, it further includes: a second capacitive element C3 for absorbing the surge signal on the high-voltage bus. The second capacitive element C3 is connected in series with the first capacitive element C2.

[0085] In this embodiment, in order to adapt to the high-voltage bus, when the voltage of the high-voltage bus is relatively large, the second capacitive element C3 is connected in series on the basis of the first capacitive element C2 to improve the absorption ability of the surge signal of the high-voltage bus.

[0086] In an embodiment of the present invention, further, as Figures 2 to 9 shown, it further includes: a third resistive element R3 for releasing the surge signal in the second capacitive element C3. The third resistive element R3 is connected in parallel with the second capacitive element C3.

[0087] In this embodiment, when the second capacitive element C3 is provided, the third resistive element R3 is provided to cooperate with the second resistive element R2 to balance the voltages across the first capacitive element C2 and the second capacitive element C3. At the same time, the third resistive element R3 is also used to release the surge signal on the second capacitive element C2, thereby improving the reliability of the drive control circuit.

[0088] In an embodiment of the present invention, as Figures 2 to 9 shown, further, it further includes: a fourth resistive element for restricting the current flowing through at least one of the first capacitive element, the second capacitive element, and / or the first resistive element R1; a fourth resistive element R4 for restricting the current flowing through the first capacitive element C2 and / or the second capacitive element C3; the fourth resistive element R4, the first capacitive element C2, and the unidirectional conduction element are connected in series between the high-voltage bus and the low-voltage bus; or the fourth resistive element R4, the first capacitive element C2, the second capacitive element C3, and the unidirectional conduction element are connected in series between the high-voltage bus and the low-voltage bus; or the unidirectional conduction element D1 and the fourth resistive element R4 are connected in series and are connected in series between the high-voltage bus and the low-voltage bus through the first capacitive element C2 and / or the second capacitive element C3 and through the first resistive element R1, the switching element 104, and the current measuring element 112.

[0089] In this embodiment, the setting of the fourth resistive element R4 restricts the current flowing through the circuit where it is located, avoids the situation of excessive instantaneous current, thereby causing component damage, and improves the reliability of the drive control circuit. At the same time, the fourth resistive element R4 also functions to absorb the surge signal in the circuit where it is located, thereby improving the surge signal absorption ability of the drive control circuit.

[0090] In any of the above embodiments, the current measuring element 112 is a Hall sensor or a resistive element.

[0091] Among them, the manufacturing process of the Hall sensor is mature and the cost is low.

[0092] In an embodiment of the present invention, as Figure 2As shown, when the prototype is powered on, the input voltage is rectified by the rectifier circuit 114 and then charges the bus capacitor C1, the first capacitive element C2, and the second capacitive element C3 simultaneously. At this time, if the input voltage is within the normal set range (150V - 264V) and does not exceed 294V (the set hardware protection voltage threshold Vref is 800V, and the software protection threshold is 720V, and the corresponding AC input effective value is 720 / 1.414 / 1.732), the prototype operates normally, and the switching element 104 of the first resistive element R1 is not turned on. After the charging is completed, the voltage across the first resistive element R1 stabilizes at the Vdc-max value (that is, the voltage across the first resistive element R1 stabilizes at the maximum value Vdc-max of the bus voltage, or changes slowly). Further, as Figure 9 shown, the current measurement element 112 samples the current signal, which can be obtained by measuring the ratio of the voltage across the first resistive element R1 to the first resistive element R1.

[0093] When the prototype is operating normally, the voltage on the bus capacitor C1 fluctuates at a frequency six times the frequency of the AC input power supply. When operating normally, the maximum value of the bus voltage is 264×1.414×1.732 = 646V, which is much smaller than the set protection threshold. Therefore, the switching element 104 of the first resistive element R1 will not function.

[0094] 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 inductor, and the kinetic energy of the compressor; when a surge comes, due to the limited surge absorption capacity of the small-capacity bus capacitor C1 (film capacitor or small-capacity electrolytic capacitor), the bus voltage will rise rapidly. When the DC bus voltage is higher than the set threshold voltage V2 (set here as 720V, which can be actually adjusted), the DC bus voltage passes through the voltage-dividing resistors R6 and R7, and the divided bus voltage enters the AD port of the control chip 108 (MCU, micro controller unit micro control unit) (the sampling signal entering the MCU is Vdc) and the input terminal of the comparator. When the divided bus voltage is greater than the set threshold of the comparison circuit 106, the output of the comparison circuit 106 (comparator) changes from high level to low level, and the level change signal enters the external interrupt port of the MCU. The advantage of using the level change signal output by the comparator is that the response speed is fast enough and it is not affected by software interference. It is also possible to set a fixed high-frequency interrupt in the software of the control chip 108, such as an interrupt frequency of 40K. In this interrupt program, the DC bus voltage is sampled, and it is judged whether it exceeds the set threshold according to the sampled value.

[0095] As Figures 14 to 19 shown, when the MCU receives the external interrupt signal and judges that the current bus voltage exceeds 720V, the compressor starts to operate at a reduced power or stops, as Figure 16As shown, the MCU starts to output pulse width modulation with a carrier frequency of 40K (since the bandwidth of the Hall sensor is 120K and the sampling delay is 8us, the minimum duty cycle limit of the pulse width modulation is 60%. If a smaller carrier frequency is selected, the corresponding duty cycle can be further reduced) or as Figure 14 shown, a pulse signal (sampled at a fixed period such as 40K) controls the switching element of the absorption resistor. If it is pulse width modulation control, as Figure 17 shown, the current is sampled at the midpoint of each pulse width modulation conduction. If it is a pulse control signal, as Figure 15 shown, the current is sampled at a fixed sampling period.

[0096] If it is pulse width modulation duty cycle control, the total absorbed energy ∑E is obtained by adding the current Isample sampled each time with Isample×Isample×R×duty×T (where R is the resistance value of the corresponding resistive element, duty is the pulse width modulation duty cycle, and T is the period of the pulse width modulation. The value calculated by the above formula is the energy absorbed each time the switching element conducts). If the formula ∑E≦0.7×5 (5 is the rated power of a single resistor, 5W, and 0.7 is the safety factor) is satisfied, the output continues; if it is pulse control, the total absorbed energy ∑E is obtained by adding the current Isample sampled each time with Isample×Isample×R×△t (△t is the current sampling period). If the formula ∑E≦0.7×5 is satisfied, the output continues.

[0097] In addition, since the drive control circuit has a sampling function, the sampled current of the first resistive element can be obtained (since the overcurrent of the IGBT itself within 1ms is greater than the rated current, the maximum delay from sampling to judging overcurrent and turning off the output is one sampling period, which can provide timely protection). When the actual sampled current is greater than the set protection threshold, the switching element of the first resistive element R1 is directly turned off.

[0098] Specifically, due to the intervention of the first resistive element R1, the bus voltage will drop rapidly. When it is lower than a certain fixed threshold (such as 700V) or the formula ∑E≦0.7×5 is not satisfied (if the sampled current has always been normal and does not exceed the set threshold), the MCU controls the switching element 104 of the first resistive element R1 to disconnect, and the first resistive element R1 no longer functions. Here, 0.7 is the safety factor, which can be changed according to the circuit. At the same time, the formula ∑E≦0.7×5 can also be judged by the relationship curve between the absorption power of the resistor and time. For example Figure 16 the curve form. If the first resistive element R1 is selected to be 0.1 ohm to 24 ohms, the energy absorbed by the pulse within 1ms can be limited to 80000W×1ms = 80J.

[0099] By controlling the first resistive element R1 to always control the switching element 104 with the maximum allowable instantaneous power, the purpose of absorbing the surge at the fastest speed is achieved.

[0100] It should be noted that the selection of the carrier frequency and the duty cycle is mainly determined by the set operating threshold V2, the resistance value of the first resistive element R1, the rated power of the first resistive element R1, and the instantaneous overload capacity (which will be reflected in the resistor specification sheet). Generally speaking, the greater the rated power of the first resistive element R1, the greater its instantaneous overload capacity. Therefore, under the same operating threshold V2, the greater the duty cycle that can be turned on or the smaller the carrier frequency (i.e., the larger the period).

[0101] Specifically, the duty cycle is given by a formula, such as (Vdc-filter / V2)×T (where Vdc-filter is the voltage value obtained by filtering the real-time detected bus voltage). At the same time, a duty cycle limiting link is added. The greater the bus voltage, the greater the output duty cycle. A high bus voltage and a high duty cycle can quickly absorb surge energy; other formulas can also be used, such as the greater the bus voltage, the smaller the output duty cycle, to ensure the reliability of the absorption resistor, etc.

[0102] Regarding the conduction threshold voltage (set to fixed 720V and 700V here), it can be a floating value (such as detecting the Vdc-max value in the previous few detection cycles (such as 100ms) (Vdc-max is the maximum value of the bus voltage in the previous few detection cycles), and using this value plus deltaV1 as the turn-off voltage threshold of the switching element, and using Vdc-max + △V1 + 20V (where deltaV1 is the floating value of the voltage, set according to the tolerance of component damage in the drive control circuit, and 20V can be other values) as the conduction voltage threshold of the switching element 104. Of course, it can also be extended to detect the peak value of the AC input, using the AC input peak value Vac-max + △V1 as the conduction voltage threshold of the switching element, and using Vdc-max + △V1 + 20V (which can be other values) as the conduction voltage threshold of the switching element.

[0103] The judgment of overvoltage and exiting overvoltage is currently to generate a level conversion by comparing with a set threshold through a hardware comparator to judge overvoltage, and the software real-time detects that the bus voltage (Vdc-filter) after filtering is lower than a certain value set as exiting overvoltage; both overvoltage and exiting overvoltage are given by a hardware hysteresis comparator.

[0104] As Figures 10 to 13 shown, R5 is the system damping resistor (not greater than 200 ohms). If it is an area without harmonic requirements, Ldc is preferably a small inductor (for cost reasons). If a small inductor is selected, it is best to match the system damping resistor to improve the system stability.

[0105] The resistance value of the first resistive element R1 is related to the set bus voltage protection threshold and the overcurrent capacity of the switching element 104.

[0106] The selection of the fourth resistive element R4 and the first capacitive element C2 is related to the inductance of the first resistive element R1. If the first resistive element R1 is a non-inductive resistor, the fourth resistive element R4, the first capacitive element C2, and the discharge element 110 (as Figure 13 shown) can be not used.

[0107] The selection of the discharge element 110 (antiparallel diode) is related to the inductance and resistance value of the first resistive element R1.

[0108] In any of the above embodiments, further, the bus capacitor C1 is a thin film capacitor.

[0109] In an embodiment of the present invention, as Figure 2 shown, the rectifier circuit 114 rectifies the AC signal and outputs it as the voltage signal of the high-voltage bus. The sampling circuit is specifically used to collect the peak voltage signal of the AC power input before the rectifier circuit 114 and / or the voltage signal before the reactor after the rectifier circuit 114 and / or the voltage signal before the inverter bridge 102 after the reactor Ldc.

[0110] In this embodiment, the sampling circuit is specifically used to collect the peak voltage signal of the AC power V AC input before the rectifier circuit 114 and / or the voltage signal before the reactor Ldc after the rectifier circuit 114 and / or the voltage signal before the inverter bridge 102 after the reactor Ldc.

[0111] Optionally, the drive control circuit includes a power filter module. The power filter module is connected in series between the AC power supply and the rectifier circuit 114. The sampling circuit is specifically used to collect the peak voltage signal of the AC power input before the power filter module and / or the voltage signal before the rectifier circuit 114 after the power filter module.

[0112] In a specific embodiment of the present invention, the capacitance value of the thin film capacitor is lower than the preset capacitance value, where the preset capacitance value is calculated according to the following calculation formula:

[0113]

[0114] where C dc is the preset capacitance, 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, and v dc0is the average value of the bus voltage. For example, taking the 7P prototype as an example, C can be determined according to this calculation formula dc must be greater than 840 uF, and the preset capacity is above 840 uF. In specific implementation, 1230 uF is used.

[0115] An embodiment of the second aspect of the present invention provides an air conditioner, including: a motor; and 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. Therefore, the air conditioner has all the beneficial effects of the drive control circuit described in any of the above embodiments, which will not be elaborated here.

[0116] In the description of this specification, the descriptions of terms such as "one embodiment", "some embodiments", "specific embodiments", etc. mean 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.

[0117] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. 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: Inverter bridge, the inverter bridge drives and controls the load to operate, and the inverter bridge is connected between the high-voltage bus and the low-voltage bus. It is characterized by including: A reactor for absorbing the surge signal 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, which is used to provide the starting voltage required for the load to be powered on, and the bus capacitor is also used to absorb the surge signal. The bus capacitor is connected to the bus line on the input side of the inverter bridge; A sampling circuit for collecting the voltage signal of the high-voltage bus; A first resistive element, a switching element, and a current measuring element. The switching element is configured to control the first resistive element to absorb the surge signal on the high-voltage bus. The current measuring element is used to measure the current signal flowing through the first resistive element. The first resistive element, the switching element, and the current measuring element are connected in series between the high-voltage bus and the low-voltage bus; A control chip for detecting and confirming that the current signal is greater than a preset current threshold, and stopping driving the switching element so that the first resistive element stops absorbing the surge signal. The control chip is respectively connected to the sampling circuit and the current measuring element; The control chip is further used for: Detecting and confirming that the voltage signal of the high-voltage bus is less than a first preset threshold, and stopping driving the switching element so that the first resistive element stops absorbing the surge signal; and Detecting and confirming that the voltage signal of the high-voltage bus is greater than or equal to a second preset threshold, and controlling the switching element to operate according to a preset specified duty cycle or a preset specified conduction time or a preset specified carrier frequency, so that the first resistive element absorbs the surge signal. The first preset threshold is less than the second preset threshold; The bus capacitor is a thin-film capacitor; The capacitance value of the thin-film capacitor is less than a preset capacitance value, where the preset capacitance value is calculated according to the following calculation formula: Among them, 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; The control chip is further used for: Detecting and confirming that the absorption power of the first resistive element is greater than the preset power threshold, and stopping driving the switching element so that the first resistive element stops absorbing the surge signal; Wherein, the absorption power is calculated by the bus voltage and the resistance value of the first resistive element, and the absorption power is Vdc×Vdc / R, where Vdc is the bus voltage and R is the resistance value of the first resistive element.

2. The drive control circuit according to claim 1, characterized in that, It further includes: A first capacitive element for absorbing the surge signal on the high-voltage bus. The first capacitive element is connected in series between the high-voltage bus and the low-voltage bus.

3. The drive control circuit according to claim 2, wherein It further includes: A unidirectional conduction element configured to control the first capacitive element to absorb the surge signal on the high-voltage bus, the first capacitive element being connected in series with the unidirectional conduction element; or the unidirectional conduction element is configured to control the first capacitive element and / or the first resistive element to absorb the surge signal on the high-voltage bus, the unidirectional conduction element being connected in series with the first capacitive element, and the first resistive element, the switching element, and the current measuring element are connected to the high-voltage bus through the unidirectional conduction element.

4. The drive control circuit according to claim 2, wherein Further comprising: A second resistive element for releasing the surge signal in the first capacitive element, the second resistive element being connected in parallel with the first capacitive element.

5. The drive control circuit according to claim 1, characterized in that Further comprising: A comparison circuit for detecting and confirming that the voltage signal of the high-voltage bus is greater than or equal to a third preset threshold, the comparison circuit outputting a level inversion signal capable of triggering a port of the control chip, and the control chip switching the control signal of the switching element according to the level inversion signal to adjust the absorption speed of the first resistive element for the surge energy, the comparison circuit being connected to the sampling circuit and the control chip respectively.

6. The drive control circuit according to claim 3, wherein Further comprising: A second capacitive element for absorbing the surge signal on the high-voltage bus, the second capacitive element being connected in series with the first capacitive element.

7. The drive control circuit according to claim 6, wherein Further comprising: A third resistive element for releasing the surge signal in the second capacitive element, the third resistive element being connected in parallel with the second capacitive element.

8. The drive control circuit according to claim 6, characterized in that, Further comprising: A fourth resistive element for limiting the current flowing through at least one of the first capacitive element, the second capacitive element, and the first resistive element; The fourth resistive element, the first capacitive element, and the unidirectional conduction element are connected in series and then connected between the high-voltage bus and the low-voltage bus; or the fourth resistive element, the first capacitive element, the second capacitive element, and the unidirectional conduction element are connected in series and then connected between the high-voltage bus and the low-voltage bus; or the unidirectional conduction element is connected in series with the fourth resistive element and then connected between the high-voltage bus and the low-voltage bus through the first capacitive element and / or the second capacitive element and through the first resistive element, the switching element, and the current measuring element.

9. The drive control circuit according to claim 1, wherein The current measuring element is a Hall sensor or a resistive element.

10. The drive control circuit according to claim 1, wherein Further comprising: A rectifying circuit that rectifies the AC signal and outputs it as the voltage signal of the high-voltage bus.

11. An air conditioner, characterized in that, Comprising: A motor; The drive control circuit according to any one of claims 1 to 10, a signal input terminal of the motor being connected to the drive control circuit, and the drive signal output by the drive control circuit being used to drive the motor to operate.

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