Motor drive circuit and air conditioning equipment

Abstract

This application relates to a motor drive circuit and an air conditioning device. The motor drive circuit includes: when the air conditioner is off or powered off, a current discharge circuit connects a consumable component to the bus in parallel with the bus capacitor. Since the resistance of the consumable component is less than the capacitive reactance of the bus capacitor, most of the current corresponding to the back electromotive force fed back by the inverter will flow through the cement resistor for consumption, while the current flowing into the bus capacitor is greatly reduced. This avoids the bus capacitor receiving a large amount of current in a short period of time, which would cause the bus voltage to rise rapidly. Therefore, the motor drive circuit based on the above structure can solve the problem of bus voltage back surge caused by the air conditioner being off or powered off.

Description

Technical Field

[0001] This application relates to the field of air conditioning technology, and in particular to a motor drive circuit and an air conditioning device. Background Technology

[0002] Currently, inverter technology is being widely adopted in both residential and commercial air conditioners, and its reliability is receiving increasing attention. When the unit is off or powered off, the motor in the air conditioning unit reverses direction, causing the inverter to rapidly switch from a high-voltage output state under weak field control to a state where the generator feeds energy back to the bus. This can cause the bus voltage to rise rapidly, resulting in voltage spikes. This can lead to abnormal fan start-up control, and when the voltage spike reaches a certain value, there is a risk of damaging the inverter bridge power devices. Utility Model Content

[0003] This application provides a motor drive circuit and an air conditioning device to solve the problem of bus voltage spikes when the air conditioner is turned off or powered off.

[0004] In a first aspect, this application provides a motor drive circuit, which includes a rectifier circuit, a control unit, a current discharge circuit, and an inverter circuit. The rectifier circuit is connected to the inverter circuit via the current discharge circuit. The control unit is connected to both the current discharge circuit and the inverter circuit. The inverter circuit is also connected to a motor. The rectifier circuit includes a bus capacitor, the voltage of which is the bus voltage. The current discharge circuit includes a consumable component, the resistance of which is less than the capacitive reactance of the bus capacitor.

[0005] When the control unit receives a power-off signal, it outputs a discharge signal to the current discharge circuit, or the rectifier circuit outputs a discharge signal to the current discharge circuit in a power-off state. Based on the discharge signal, the current discharge circuit connects the consumption component to the bus circuit and connects it in parallel with the bus capacitor. The inverter circuit sends the back electromotive force fed back by the motor in reverse to the consumption component for consumption.

[0006] Optionally, the current discharge circuit includes a voltage divider control circuit, a shutdown control circuit, a discharge control circuit, and the consumable component. The first terminal of the voltage divider control circuit is connected to the first terminal of the bus capacitor and the first terminal of the consumable component. The second terminal of the voltage divider control circuit is connected to the first terminal of the shutdown control circuit and the discharge control circuit. The second terminal of the discharge control circuit is connected to the second terminal of the consumable component. The discharge control circuit is used to control the connection relationship between the consumable component and the bus capacitor.

[0007] Optionally, the shutdown control circuit includes a first transistor. The base of the first transistor is connected to the output terminal of the control unit through a current-limiting resistor. The emitter of the first transistor is connected to the second terminal of the voltage divider control circuit and the first terminal of the discharge control circuit. The collector of the first transistor is connected to the driving power supply. When the first transistor receives the discharge signal output by the control unit, it switches to the on state and outputs a conduction signal to the discharge control circuit. The discharge control circuit connects the consumable component to the bus circuit in parallel with the bus capacitor based on the conduction signal.

[0008] Optionally, the voltage divider control circuit includes a first voltage divider resistor, a second voltage divider resistor, and a second transistor. The first terminal of the first voltage divider resistor is connected to the first terminal of the bus capacitor and the first terminal of the consumable component. The second terminal of the first voltage divider resistor is connected to the first terminal of the second voltage divider resistor and the base of the second transistor. The second terminal of the second voltage divider resistor is connected to the second terminal of the bus capacitor. The emitter of the second transistor is connected to the emitter of the first transistor and the discharge control circuit. When the second transistor receives the discharge signal through the first and second voltage divider resistors, it switches to the on state and outputs a conduction signal to the discharge control circuit. Based on the conduction signal, the discharge control circuit connects the consumable component to the bus circuit in parallel with the bus capacitor.

[0009] Optionally, the discharge control circuit includes a discharge power switch, the gate of which is connected to the emitter of the first transistor and the emitter of the second transistor, respectively, the collector of which is connected to the first terminal of the consumable component, and the emitter of which is connected to the second terminal of the bus capacitor. When the discharge power switch receives the discharge signal, it switches to the on state to connect the consumable component in the bus circuit in parallel with the bus capacitor.

[0010] Optionally, the consumable component includes a cement resistor and a bleeder diode. The first end of the cement resistor is connected to the collector of the power switch and the positive terminal of the bleeder diode, respectively. The second end of the cement resistor is connected to the first end of the bus capacitor and the negative terminal of the bleeder diode, respectively.

[0011] Optionally, the rectifier circuit includes a filter circuit, a three-phase rectifier bridge, and the bus capacitor connected in series. The filter circuit filters the three-phase AC input power supply into a three-phase filtered voltage and outputs it to the three-phase rectifier bridge. The three-phase rectifier bridge rectifies the three-phase filtered voltage into a DC voltage and outputs it to the bus capacitor. The bus capacitor regulates the DC voltage to the bus voltage.

[0012] Optionally, the filtering circuit includes three filtering inductors, each of which is connected to one phase of AC input power; the three-phase rectifier bridge includes three parallel rectifier branches, each of which includes two rectifier diodes connected in series, and the connection point between the two rectifier diodes in each rectifier branch is connected to one phase of AC input power through one of the filtering inductors.

[0013] Optionally, the inverter circuit includes a first power switch, a second power switch, a third power switch, a fourth power switch, a fifth power switch, and a sixth power switch. A freewheeling diode is connected between the emitter and collector of each power switch. The connection point between the source of the first power switch and the drain of the fourth power switch is connected to the control unit. The source of the second power switch and the drain of the fifth power switch are connected to the control unit.

[0014] Secondly, this application provides an air conditioning device, which includes a motor and the motor drive circuit described in any of the above claims.

[0015] The motor drive circuit provided in this application embodiment includes a rectifier circuit, a control unit, a current discharge circuit, and an inverter circuit. The rectifier circuit is connected to the inverter circuit via the current discharge circuit. The control unit is connected to both the current discharge circuit and the inverter circuit. The inverter circuit is also connected to the motor. The rectifier circuit includes a bus capacitor, the voltage of which is the bus voltage. The current discharge circuit includes a dissipation component, the resistance of which is less than the capacitive reactance of the bus capacitor. When the control unit receives a shutdown signal, it outputs a discharge signal to the current discharge circuit. Alternatively, the rectifier circuit outputs a discharge signal to the current discharge circuit when the power is off. Based on the discharge signal, the current discharge circuit connects the dissipation component to the bus circuit in parallel with the bus capacitor. The inverter circuit sends the back electromotive force fed back by the motor in reverse to the dissipation component for dissipation.

[0016] Based on the above structure, when the air conditioner is off or powered off, the current discharge circuit connects the consuming components to the bus in parallel with the bus capacitor. Since the resistance of the consuming components is less than the capacitive reactance of the bus capacitor, most of the current corresponding to the back electromotive force fed back by the inverter will flow through the cement resistor for consumption, while the current flowing into the bus capacitor is greatly reduced. This avoids the bus capacitor receiving a large amount of current in a short period of time, which would cause the bus voltage to rise rapidly. Therefore, the motor drive circuit based on the above structure can solve the problem of bus voltage back surge caused by the air conditioner being off or powered off. Attached Figure Description

[0017] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the present invention and, together with the description, serve to explain the principles of the present invention.

[0018] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] One or more embodiments are illustrated by way of example with reference numerals in the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Elements with the same reference numerals in the drawings are denoted as similar elements. Unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0020] Figure 1 This is a schematic diagram of the structure of a motor drive circuit provided in an embodiment of this application;

[0021] Figure 2 This is a schematic diagram of the structure of a motor drive circuit provided in an embodiment of this application;

[0022] Figure 3 This is a schematic diagram of a motor drive circuit provided in an embodiment of this application. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0024] The following disclosure provides numerous different embodiments or examples for implementing various structures of the present invention. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the scope of the invention. Furthermore, reference numerals and / or letters may be repeated in different examples. Such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed.

[0025] In one embodiment, Figure 1This is a schematic diagram of the structure of a motor 140 drive circuit in one embodiment, with reference to... Figure 1 The motor 140 drive circuit is used in a frequency converter, which is used in air conditioning equipment. The motor 140 drive circuit specifically includes a rectifier circuit 110, a control unit 150, a current discharge circuit 120, and an inverter circuit 130. The rectifier circuit 110 is connected to the inverter circuit 130 through the current discharge circuit 120. The control unit 150 is connected to the current discharge circuit 120 and the inverter circuit 130 respectively. The inverter circuit 130 is also connected to the motor 140. The rectifier circuit 110 includes a bus capacitor C1, and the voltage of the bus capacitor C1 is the bus voltage. The current discharge circuit 120 includes a consumable component 1201, and the resistance of the consumable component 1201 is less than the capacitive reactance of the bus capacitor C1.

[0026] When the control unit 150 receives a power-off signal, it outputs a discharge signal to the current discharge circuit 120, or the rectifier circuit 110 outputs a discharge signal to the current discharge circuit 120 in a power-off state. Based on the discharge signal, the current discharge circuit 120 connects the consumption component 1201 to the bus circuit and connects it in parallel with the bus capacitor C1. The inverter circuit 130 sends the back electromotive force fed back by the motor 140 in reverse to the consumption component 1201 for consumption.

[0027] Specifically, under normal circumstances, the rectifier circuit 110 rectifies and filters the AC power supplied by the AC power source, thereby converting the AC power into DC power and supplying it to the bus. At this time, the control unit 150 outputs a normal drive signal to the current discharge circuit 120. The connection between the consumption component 1201 in the current discharge circuit 120 and the bus is cut off. At this time, the consumption component 1201 is not connected to the bus circuit, and the consumption component 1201 will not consume the bus voltage of the bus circuit.

[0028] When the device is powered off, the control unit 150 outputs a discharge signal to the current discharge circuit 120 based on the power-off signal (i.e., ...). Figure 2 or Figure 3 The DSP control signal in the circuit is used to connect the consuming component 1201 to the bus circuit and connect it in parallel with the bus capacitor C1. At this time, the back electromotive force fed back by the motor 140 is transmitted to the current discharge circuit 120 through the inverter circuit 130. Since the resistance of the consuming component 1201 is less than the capacitive reactance of the bus capacitor C1, most of the current corresponding to the back electromotive force fed back by the inverter by the motor 140 will flow through the cement resistor R4 for consumption, while the current flowing into the bus capacitor C1 is greatly reduced. The voltage of the bus capacitor C1 corresponds to the bus voltage, thereby avoiding the bus voltage from rising rapidly due to the bus capacitor C1 receiving a large amount of current in a short period of time.

[0029] When a power outage occurs, i.e., the rectifier circuit 110 outputs a discharge signal to the current discharge circuit 120. Based on this discharge signal, the current discharge circuit 120 connects the consuming component 1201 to the bus circuit in parallel with the bus capacitor C1. At this time, the back electromotive force fed back by the motor 140 is transmitted to the current discharge circuit 120 through the inverter circuit 130. Since the resistance of the consuming component 1201 is less than the capacitive reactance of the bus capacitor C1, most of the current corresponding to the back electromotive force fed back by the inverter from the motor 140 will flow through the cement resistor R4 for consumption, while the current flowing into the bus capacitor C1 is greatly reduced. The voltage of the bus capacitor C1 corresponds to the bus voltage, thereby avoiding the rapid rise of the bus voltage caused by the bus capacitor C1 receiving a large amount of current in a short period of time. Therefore, the motor 140 drive circuit based on the above structure can solve the problem of bus voltage back surge peak caused by the air conditioner when it is turned off or in a power outage state.

[0030] The component 1201 is connected in parallel to the bus circuit. By utilizing its small resistance value, it provides a low-impedance shunt branch for the current of the motor 140 corresponding to the back electromotive force. This allows the current of the motor 140 to consume electrical energy mainly on itself, reducing the energy flowing into the bus capacitor C1. This effectively avoids a sudden voltage rise in the bus capacitor C1, ensuring the voltage stability of the bus circuit and the safety of the system.

[0031] In one embodiment, refer to Figure 2 The current discharge circuit 120 includes a voltage divider control circuit 1202, a shutdown control circuit 1203, a discharge control circuit 1204, and the consumable component 1201. The first terminal of the voltage divider control circuit 1202 is connected to the first terminal of the bus capacitor C1 and the first terminal of the consumable component 1201. The second terminal of the voltage divider control circuit 1202 is connected to the first terminal of the shutdown control circuit 1203 and the first terminal of the discharge control circuit 1204. The second terminal of the discharge control circuit 1204 is connected to the second terminal of the consumable component 1201. The discharge control circuit 1204 is used to control the connection relationship between the consumable component 1201 and the bus capacitor C1.

[0032] Specifically, the voltage divider control circuit 1202 in the current discharge circuit 120 is used to receive the discharge signal provided by the rectifier circuit 110, and the shutdown control circuit 1203 is used to receive the discharge signal provided by the control unit 150. The voltage divider control circuit 1202 or the shutdown control circuit 1203 provides the received discharge signal to the discharge control circuit 1204. The discharge control circuit 1204 is used to control the on / off state between the consumption component 1201 and the bus circuit. The discharge control circuit 1204 controls the establishment of a connection between the consumption component 1201 and the bus circuit based on the discharge signal. When no discharge signal is received, the discharge control circuit 1204 controls the disconnection between the consumption component 1201 and the bus circuit to avoid additional losses.

[0033] In one embodiment, refer to Figure 2 The shutdown control circuit 1203 includes a first transistor Q1. The base of the first transistor Q1 is connected to the output terminal of the control unit 150 through a current-limiting resistor R3. The emitter of the first transistor Q1 is connected to the second terminal of the voltage divider control circuit 1202 and the first terminal of the discharge control circuit 1204, respectively. The collector of the first transistor Q1 is connected to the driving power supply. When the first transistor Q1 receives the discharge signal output by the control unit 150, it switches to the conduction state and outputs a conduction signal to the discharge control circuit 1204. Based on the conduction signal, the discharge control circuit 1204 connects the consumable component 1201 to the bus circuit in parallel with the bus capacitor C1.

[0034] Specifically, the shutdown control circuit 1203 includes a first transistor Q1 and a current-limiting resistor R3. Under normal operating conditions, the control unit 150 provides a high-level signal to the first transistor Q1 through the current-limiting resistor R3, making the base of the first transistor Q1 high. At this time, the emitter junction of the first transistor Q1 is reverse biased, and the first transistor Q1 is not conducting, which is equivalent to the switch being open. This will not affect the conduction of the subsequent current discharge circuit 120, and thus will prevent the discharge control circuit 1204 from connecting the consumable component 1201 to the bus circuit.

[0035] When the power is off, the control unit 150 provides a low-level signal to the first transistor Q1 through the current-limiting resistor R3, that is, a low-level discharge signal, thereby pulling down the base of the first transistor Q1 and turning on the first transistor Q1. In turn, the first transistor Q1 outputs a high-level conduction signal to the discharge control circuit 1204. Based on the conduction signal, the discharge control circuit 1204 connects the energy-consuming component 1201 to the bus circuit. At this time, the motor 140 is converted from a motor to a generator 140, and the voltage corresponding to the induced electromotive force is higher than the bus voltage. The current of the motor 140 corresponding to the back electromotive force is fed back to the bus through the inverter circuit 130. If there is no suitable energy-consuming component, all the energy fed back to the bus will flow into the bus capacitor C1, causing the voltage of the bus capacitor C1 to rise rapidly.

[0036] When the discharge control circuit 1204 establishes a connection between the consumption component 1201 and the bus circuit, according to the characteristics of parallel circuits, the voltage of each branch in the parallel circuit is equal, and the total current is equal to the sum of the currents of each branch. At this time, the bus circuit includes two parallel branches: one is the bus capacitor C1 branch, and the other is the consumption component 1201 branch. The motor 140 current will be distributed according to the impedance of the two branches. Since the resistance of the consumption component 1201 is relatively small compared to the capacitive reactance of the bus capacitor C1, the equivalent capacitive reactance of the capacitor is relatively small at the moment of energy feedback of the motor 140, but it is still larger than the resistance of the consumption component 1201. Therefore, most of the motor 140 current will flow through the consumption component 1201. The motor 140 current flowing through the consumption component 1201 will generate power in the consumption component 1201, thereby converting electrical energy into heat energy for consumption. In this way, most of the energy fed back to the busbar motor 140 is consumed by the energy-consuming component 1201, and the energy flowing into the busbar capacitor C1 is greatly reduced, thereby avoiding a rapid voltage rise in the busbar capacitor C1 due to a large amount of charging in a short period of time.

[0037] In one embodiment, refer to Figure 2 The voltage divider control circuit 1202 includes a first voltage divider resistor R1, a second voltage divider resistor R2, and a second transistor Q2. The first end of the first voltage divider resistor R1 is connected to the first end of the bus capacitor C1 and the first end of the consumable component 1201. The second end of the first voltage divider resistor R1 is connected to the first end of the second voltage divider resistor R2 and the base of the second transistor Q2. The second end of the second voltage divider resistor R2 is connected to the second end of the bus capacitor C1. The emitter of the second transistor Q2 is connected to the emitter of the first transistor Q1 and the discharge control circuit 1204. When the second transistor Q2 receives the discharge signal through the first voltage divider resistor R1 and the second voltage divider resistor R2, it switches to the on state and outputs an on signal to the discharge control circuit 1204. Based on the on signal, the discharge control circuit 1204 connects the consumable component 1201 to the bus circuit and connects it in parallel with the bus capacitor C1.

[0038] Specifically, the voltage divider control circuit 1202 includes two voltage divider resistors and a second transistor Q2. The voltage divider control circuit 1202 receives the voltage divider signal from the bus voltage through the voltage divider resistors. Based on this voltage divider signal, it detects whether the bus voltage is in a power-down state. When a power-down state occurs, the voltage divider signal becomes the discharge signal. At the instant of power failure, the motor 140 continues to rotate due to the relationship, and will feed energy back to the bus through back electromotive force, causing the bus voltage to drop slower than the switching power supply VCC. At this time, the base voltage of the second transistor Q2 comes from the voltage divider signal of the bus voltage, therefore it drops more slowly. The emitter voltage of Q2 drops rapidly relative to the base voltage due to the discharge of the energy storage capacitor. At this time, the conduction condition of the second transistor Q2 is met, so the second transistor Q2 will conduct. The conducting second transistor Q2 outputs a conduction signal to the discharge control circuit 1204. Based on the conduction signal, the discharge control circuit 1204 connects the consumption component 1201 into the bus circuit and connects it in parallel with the bus capacitor C1, thereby receiving most of the current from the motor 140 for consumption. The energy flowing into the bus capacitor C1 is greatly reduced, thereby avoiding the rapid voltage rise of the bus capacitor C1 due to a large amount of charging in a short period of time.

[0039] In one embodiment, refer to Figure 2 The discharge control circuit 1204 includes a discharge power switch V7. The gate of the discharge power switch V7 is connected to the emitter of the first transistor Q1 and the emitter of the second transistor Q2, respectively. The collector of the discharge power switch V7 is connected to the first terminal of the consumption component 1201, and the emitter of the discharge power switch V7 is connected to the second terminal of the bus capacitor C1. When the discharge power switch V7 receives the discharge signal, it switches to the on state to connect the consumption component 1201 in the bus circuit in parallel with the bus capacitor C1.

[0040] Specifically, the discharge power switch V7 is an IGBT switch. Under normal circumstances, the control unit 150 sends a high-level signal to the base of the first transistor Q1. At this time, the first transistor Q1 is in the off state, and the gate of the discharge power switch V7 does not receive the initial low-level drive signal. At the same time, the second transistor Q2 is in the off state because its base voltage is higher than its collector voltage VCC, and it will not provide a high-level conduction signal to the discharge power switch V7. The gate of the discharge power switch V7 is in the off state because it has no high-level drive. At this time, the consumable component 1201 is disconnected from the bus circuit to avoid additional losses.

[0041] When the power is off, the first transistor Q1 is turned on based on the discharge signal provided by the control unit 150, thereby providing a high-level conduction signal for the discharge power switch V7; when the power is off, the gate voltage of the second transistor Q2 is lower than the collector voltage and it is turned on, thereby providing a high-level conduction signal for the discharge power switch V7. Therefore, when the power is off or the power is off, the gate of the discharge power switch V7 will receive a high-level conduction signal and be turned on, thereby connecting the consumption component 1201 into the bus circuit to provide the current consumption function of the motor 140.

[0042] In one embodiment, refer to Figure 2 The consumable component 1201 includes a cement resistor R4 and a bleeder diode. The first end of the cement resistor R4 is connected to the collector of the power switch and the positive terminal of the bleeder diode, respectively. The second end of the cement resistor R4 is connected to the first end of the bus capacitor C1 and the negative terminal of the bleeder diode, respectively.

[0043] Specifically, when the power switch is turned on and the cement resistor R4 is connected to the bus circuit, according to the characteristics of parallel circuits, the voltage of each branch in the parallel circuit is equal, and the total current is equal to the sum of the currents in each branch. At this time, the bus circuit forms two parallel branches: one is the bus capacitor C1 branch, and the other is the cement resistor R4 branch. The motor 140 current will be distributed according to the impedance of the two branches. Since the resistance of the cement resistor R4 is relatively small compared to the capacitive reactance of the bus capacitor C1, most of the motor 140 current will flow through the cement resistor R4. When the current flows through the cement resistor R4, power is generated in the resistor, thus converting electrical energy into heat energy and dissipating it. In this way, most of the energy of the motor 140 fed back to the bus is consumed by the cement resistor R4, and the energy flowing into the bus capacitor C1 is greatly reduced, thereby avoiding a rapid voltage rise in the bus capacitor C1 due to a large amount of charging in a short period of time.

[0044] When the machine is off or powered off, the anode potential of the discharge diode is lower than the cathode potential. Due to the unidirectional conductivity of the diode, the discharge diode is in the cut-off state. It prevents the current from flowing in reverse from the branch where the cement resistor R4 is located to other parts, ensuring that the energy of the motor 140 is mainly consumed on the cement resistor R4, and there will be no abnormal current backflow interfering with the operation of other circuit parts, thus achieving effective discharge of the residual energy of the motor 140.

[0045] In one embodiment, refer to Figure 3 The rectifier circuit 110 includes a filter circuit, a three-phase rectifier bridge, and the bus capacitor C1 connected in series. The filter circuit filters the three-phase AC input power supply into a three-phase filtered voltage and outputs it to the three-phase rectifier bridge. The three-phase rectifier bridge rectifies the three-phase filtered voltage into a DC voltage and outputs it to the bus capacitor C1. The bus capacitor C1 stabilizes the DC voltage into a bus voltage.

[0046] Specifically, AC power supplies G1, G2, and G3 are connected to the three-phase rectifier bridge via a filter circuit. During normal operation, the AC power supply outputs AC power. After the filter circuit filters and suppresses current surges, the AC power is converted to DC power by the three-phase rectifier bridge. Then, after being filtered and regulated by the bus capacitor C1, a relatively smooth DC voltage is output to the bus to form the bus voltage.

[0047] In one embodiment, refer to Figure 3 The filtering circuit includes three filtering inductors, each of which is connected to one phase of AC input power. The three-phase rectifier bridge includes three parallel rectifier branches, each of which includes two rectifier diodes connected in series. The connection point between the two rectifier diodes in each rectifier branch is connected to one phase of AC input power through one of the filtering inductors.

[0048] Specifically, AC power supplies G1, G2, and G3 are connected to a rectifier bridge composed of rectifier diodes D8-D13 via inductors L4, L5, and L6 to perform rectification and filtering of the AC power supply.

[0049] In one embodiment, refer to Figure 3 The inverter circuit 130 includes a first power switch V1, a second power switch V2, a third power switch V3, a fourth power switch V4, a fifth power switch V5, and a sixth power switch V6. A freewheeling diode D14 is connected between the emitter and collector of each power switch. The connection point between the source of the first power switch V1 and the drain of the fourth power switch V4 is connected to the source of the second power switch V2 and the drain of the fifth power switch V5. The connection point between the source of the third power switch V3 and the drain of the sixth power switch V6 is connected to the source of each power switch. A freewheeling diode D14 is connected between the source and drain of each power switch. The gate of each power switch is connected to the control unit 150.

[0050] Specifically, when motor 140 is braking, decelerating, or being driven by a load, it enters a generating state (equivalent to generator 140). At this time, the electrical energy output by motor 140 cannot be consumed by the load and must be fed back to the DC bus through the circuit; otherwise, it would cause an abnormal rise in the voltage at the motor 140 terminals. However, at this time, the six power switching transistors (V1-V6) in the inverter circuit 130 are usually in the off state, because motor 140 does not require active power supply and cannot transfer energy through the conduction of the power switching transistors. However, each power switching transistor is connected in anti-parallel to a freewheeling diode D14. These six freewheeling diodes D14 automatically form a three-phase uncontrolled rectifier bridge to convert the three-phase AC power generated by motor 140 into DC power and feed it back to the bus. This DC power is then consumed by the aforementioned cement resistor R4, thereby suppressing the rise in bus voltage.

[0051] In one embodiment, an air conditioning device is provided, the air conditioning device including a motor 140 and a motor 140 drive circuit as described in any of the above embodiments.

[0052] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus a general-purpose hardware platform, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solutions, in essence or the part that contributes to the related technology, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., including several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the motor 140 drive circuit described in various embodiments or some parts of embodiments.

[0053] It should be understood that the terminology used herein is for the purpose of describing particular exemplary embodiments only and is not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms “a,” “an,” and “described” as used herein may also mean including the plural forms. The terms “comprising,” “including,” “containing,” and “having” are inclusive and therefore indicate the presence of the stated features, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, elements, components, and / or combinations thereof. The steps, processes, and operations of the motor 140 drive circuit described herein are not construed as requiring them to be performed in the specific order described or illustrated unless the order of performance is explicitly indicated. It should also be understood that alternatives or substitutions may be used.

[0054] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. An electric motor drive circuit, characterized by, The motor drive circuit includes a rectifier circuit, a control unit, a current discharge circuit, and an inverter circuit. The rectifier circuit is connected to the inverter circuit via the current discharge circuit. The control unit is connected to both the current discharge circuit and the inverter circuit. The inverter circuit is also connected to the motor. The rectifier circuit includes a bus capacitor, the voltage of which is the bus voltage. The current discharge circuit includes a consumable component, the resistance of which is less than the capacitive reactance of the bus capacitor. When the control unit receives a power-off signal, it outputs a discharge signal to the current discharge circuit, or the rectifier circuit outputs a discharge signal to the current discharge circuit in a power-off state. Based on the discharge signal, the current discharge circuit connects the consumption component to the bus circuit and connects it in parallel with the bus capacitor. The inverter circuit sends the back electromotive force fed back by the motor in reverse to the consumption component for consumption.

2. The motor drive circuit of claim 1, wherein, The current discharge circuit includes a voltage divider control circuit, a shutdown control circuit, a discharge control circuit, and the consumable component. The first terminal of the voltage divider control circuit is connected to the first terminal of the bus capacitor and the first terminal of the consumable component. The second terminal of the voltage divider control circuit is connected to the first terminal of the shutdown control circuit and the first terminal of the discharge control circuit. The second terminal of the discharge control circuit is connected to the second terminal of the consumable component. The discharge control circuit is used to control the connection relationship between the consumable component and the bus capacitor.

3. The motor drive circuit of claim 2, wherein, The shutdown control circuit includes a first transistor. The base of the first transistor is connected to the output terminal of the control unit through a current-limiting resistor. The emitter of the first transistor is connected to the second terminal of the voltage divider control circuit and the first terminal of the discharge control circuit. The collector of the first transistor is connected to the driving power supply. When the first transistor receives the discharge signal output by the control unit, it switches to the on state and outputs a conduction signal to the discharge control circuit. Based on the conduction signal, the discharge control circuit connects the consumable component to the bus circuit in parallel with the bus capacitor.

4. The motor drive circuit of claim 3, wherein, The voltage divider control circuit includes a first voltage divider resistor, a second voltage divider resistor, and a second transistor. The first terminal of the first voltage divider resistor is connected to the first terminal of the bus capacitor and the first terminal of the consumable component. The second terminal of the first voltage divider resistor is connected to the first terminal of the second voltage divider resistor and the base of the second transistor. The second terminal of the second voltage divider resistor is connected to the second terminal of the bus capacitor. The emitter of the second transistor is connected to the emitter of the first transistor and the discharge control circuit. When the second transistor receives the discharge signal through the first and second voltage divider resistors, it switches to the on state and outputs a conduction signal to the discharge control circuit. Based on the conduction signal, the discharge control circuit connects the consumable component to the bus circuit in parallel with the bus capacitor.

5. The motor drive circuit of claim 4, wherein, The discharge control circuit includes a discharge power switch. The gate of the discharge power switch is connected to the emitter of the first transistor and the emitter of the second transistor, respectively. The collector of the discharge power switch is connected to the first terminal of the consumable component. The emitter of the discharge power switch is connected to the second terminal of the bus capacitor. When the discharge power switch receives the discharge signal, it switches to the on state to connect the consumable component in the bus circuit in parallel with the bus capacitor.

6. The motor drive circuit of claim 4, wherein, The consumable components include a cement resistor and a bleeder diode. The first end of the cement resistor is connected to the collector of the power switch and the positive terminal of the bleeder diode, respectively. The second end of the cement resistor is connected to the first end of the bus capacitor and the negative terminal of the bleeder diode, respectively.

7. The motor drive circuit of claim 1, wherein, The rectifier circuit includes a filter circuit, a three-phase rectifier bridge, and the bus capacitor connected in series. The filter circuit filters the three-phase AC input power supply into a three-phase filtered voltage, which is then output to the three-phase rectifier bridge. The three-phase rectifier bridge rectifies the three-phase filtered voltage into a DC voltage and outputs it to the bus capacitor. The bus capacitor then regulates the DC voltage to the bus voltage.

8. The motor drive circuit of claim 7, wherein, The filtering circuit includes three filtering inductors, each of which is connected to one phase of AC input power. The three-phase rectifier bridge includes three parallel rectifier branches, each of which includes two rectifier diodes connected in series. The connection point between the two rectifier diodes in each rectifier branch is connected to one phase of AC input power through one of the filtering inductors.

9. The motor drive circuit of claim 8, wherein, The inverter circuit includes a first power switch, a second power switch, a third power switch, a fourth power switch, a fifth power switch, and a sixth power switch. A freewheeling diode is connected between the emitter and collector of each power switch. The connection point between the source of the first power switch and the drain of the fourth power switch is connected to the control unit. The source of the second power switch and the drain of the fifth power switch are connected to the control unit.

10. An air conditioning apparatus characterized by comprising: The air conditioning equipment includes a motor and a motor drive circuit as described in any one of claims 1-9.

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