A circuit for simultaneously implementing soft start and overvoltage protection

Abstract

The application relates to the technical field of three-phase inverter power conversion, and discloses a circuit for simultaneously realizing soft starting and overvoltage protection. When a first direct-current power supply supplies power to a motor through an inverter circuit, a soft starting circuit is turned on; when a controller detects that the voltage of the first direct-current power supply rises to a first preset value, the controller outputs a first control signal and a driving signal, a braking chopper control circuit shorts the soft starting circuit in response to the first control signal, and the inverter circuit converts direct current into alternating current to drive the motor in response to the driving signal; when the voltage detected by the controller exceeds a second preset value, the controller outputs a second control signal, an overvoltage protection circuit starts protection logic in response to the second control signal, an energy discharge path is formed relying on the soft starting circuit, meanwhile, the controller cuts off the driving signal sent to the inverter circuit, and the inverter circuit stops converting power. The application reduces hardware redundancy by multiplexing the soft starting circuit, and effectively reduces the BOM material cost of the whole machine.

Description

Technical Field

[0001] This application relates to the field of three-phase inverter power conversion technology, specifically to a circuit that simultaneously achieves soft start and overvoltage protection. Background Technology

[0002] Traditional rectifier-inverter speed control systems have two independent functional requirements: First, the need for soft-start upon power-up. The large-capacity electrolytic capacitor on the DC bus experiences a huge inrush current at power-up, which can easily damage the controller if no countermeasures are taken. Traditional solutions require additional pre-charge resistors and pre-charge relays, resulting in more components, higher costs, larger space requirements, and a high failure rate due to frequent relay aging. Second, the need for overvoltage protection during braking. When the motor decelerates rapidly or the load is suddenly unloaded, regenerative energy is generated, causing the DC bus voltage to surge. This voltage must be discharged using brake tubes and braking resistors.

[0003] However, in traditional circuits, to achieve the above two functions, the electric soft start circuit and braking circuit on the DC bus are independent of each other and have high hardware redundancy; the overall BOM (Bill of Materials) cost is high and it is not conducive to miniaturization and high power density design. Summary of the Invention

[0004] This application provides a circuit that simultaneously implements soft start and overvoltage protection to solve the problems of hardware redundancy and high BOM cost in existing circuits when simultaneously implementing soft start and overvoltage protection.

[0005] In a first aspect, this application provides a circuit that simultaneously implements soft start and overvoltage protection, the circuit comprising: a braking chopper control circuit, a soft start circuit, an overvoltage protection circuit, and a controller, wherein, The first terminal of the soft-start circuit is connected to the first DC power supply, the second terminal of the soft-start circuit is connected to the first terminal of the DC bus capacitor, and the second terminal of the DC bus capacitor is grounded. When the voltage across the DC bus capacitor exceeds a first preset value, the controller generates a first control signal and sends a drive signal to the inverter circuit of the motor; when the voltage exceeds a second preset value, it generates a second control signal and stops sending drive signals to the inverter circuit. The first terminal of the braking chopper control circuit is connected to the first output terminal of the controller, the second terminal of the braking chopper control circuit is connected to the second DC power supply, the third terminal of the braking chopper control circuit is connected to the first terminal of the soft start circuit, and the fourth terminal of the braking chopper control circuit is connected to the first terminal of the DC bus capacitor, the soft start circuit, and the inverter circuit respectively; the braking chopper control circuit receives the first control signal sent by the controller and short-circuits the soft start circuit according to the first control signal; The first terminal of the overvoltage protection circuit is connected to the second output terminal of the controller, the second terminal of the overvoltage protection circuit is connected to the soft-start circuit, and the third terminal of the overvoltage protection circuit is grounded; the overvoltage protection circuit receives the second control signal sent by the controller, and the overvoltage protection circuit releases the energy in the soft-start circuit according to the second control signal.

[0006] In one optional implementation, the soft-start circuit includes: a first resistor and a first diode, wherein, The first end of the first resistor is connected to the first DC power supply, the second end of the first resistor is connected to the anode of the first diode and the second end of the overvoltage protection circuit, and the cathode of the first diode is connected to the first end of the DC bus capacitor, the fourth end of the braking chopper control circuit and the inverter circuit.

[0007] In one optional embodiment, the overvoltage protection circuit includes a first power switch transistor, the control terminal of the first power switch transistor is connected to the second output terminal of the controller, the first terminal of the first power switch transistor is connected to the second terminal of the first resistor and the anode of the first diode, and the second terminal of the first power switch transistor is grounded.

[0008] In one optional implementation, the braking chopper control circuit includes: a second power switch and a first relay, wherein, The first relay includes a coil and a normally open contact. The first end of the normally open contact is connected to the first end of the first resistor, and the second end of the normally open contact is connected to the first end of the DC bus capacitor, the cathode of the first diode, and the inverter circuit, respectively. The first end of the coil is connected to the first end of the second power switch, and the second end of the coil is connected to the second DC power supply. The control terminal of the second power switch is connected to the first output terminal of the controller, and the second terminal of the second power switch is grounded.

[0009] In one optional embodiment, the braking chopper control circuit further includes: a second resistor, a third resistor, a first capacitor, and a second diode, wherein, The first end of the second resistor is connected to the first output terminal of the controller, and the second end of the second resistor is connected to the first end of the third resistor and the first end of the second power switch, respectively. The second terminal of the third resistor is grounded; The first capacitor is connected in parallel between the control terminal and the second terminal of the second power switch. The anode of the second diode is connected to the first end of the coil, and the cathode of the second diode is connected to the second end of the coil.

[0010] In one optional embodiment, the circuit further includes a temperature detection circuit for detecting the temperature of the first resistor and transmitting it to the controller, the controller adjusting the second control signal based on the temperature of the first resistor.

[0011] In one optional embodiment, the circuit further includes: a voltage acquisition circuit, the first terminal of which is connected to the first terminal of the DC bus capacitor, the second terminal of which is connected to the first input terminal of the controller, and the third terminal of which is grounded.

[0012] In one optional implementation, the voltage acquisition circuit includes a fourth resistor and a fifth resistor; The first end of the fourth resistor is connected to the first end of the DC bus capacitor, the second end of the fourth resistor is connected to the first end of the fifth resistor and the first input terminal of the controller, and the second end of the fifth resistor is grounded.

[0013] In one optional embodiment, the circuit further includes: a rectifier module, the input terminal of which is connected to the three-phase AC bus, the first output terminal of which is connected to the first terminal of the soft-start circuit, and the second output terminal of which is grounded; the rectifier module is used to rectify the AC power on the three-phase AC bus into DC power to provide operating voltage for the inverter circuit.

[0014] In one optional implementation, the circuit further includes an inverter circuit; The first input terminal of the inverter circuit is connected to the fourth terminal of the braking chopper control circuit, the PWM input terminal of the inverter circuit is connected to the PWM output terminal of the controller, and the output terminal of the inverter circuit is connected to the motor; the inverter circuit is used to provide three-phase AC power to the motor.

[0015] The technical solution provided by this invention has at least the following beneficial effects: The circuit provided by this invention, when the first DC power supply starts supplying power to the motor through the inverter circuit, activates the soft-start circuit. When the controller detects that the voltage of the first DC power supply has risen to a first preset value, the controller outputs a first control signal from its first output terminal to the braking chopper control circuit. The braking chopper control circuit responds to the first control signal and short-circuits the soft-start circuit, removing the restriction of the soft-start circuit on the main circuit. When the controller determines that the voltage of the first DC power supply exceeds a second preset value based on the collected voltage, the controller outputs a second control signal from its second output terminal to the overvoltage protection circuit. The overvoltage protection circuit responds to the second control signal and activates its protection logic, forming an energy discharge path based on the soft-start circuit to release excess electrical energy in the first DC power supply and suppress the continuous rise in the voltage of the first DC power supply. Therefore, this invention, by reusing the soft-start circuit, can both suppress power-on surges and perform energy discharge functions when the DC bus is overvoltaged, eliminating the need for separate soft-start and overvoltage energy discharge branches, reducing hardware redundancy, and effectively lowering the overall BOM material cost. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0017] Figure 1 This is a schematic block diagram of a circuit that simultaneously implements soft start and overvoltage protection according to an embodiment of this application; Figure 2 This is a schematic diagram of a circuit that simultaneously implements soft start and overvoltage protection according to an embodiment of this application. Detailed Implementation

[0018] 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.

[0019] It is understood that before using the technical solutions disclosed in the various embodiments of this application, users should be informed of the types, scope of use, and usage scenarios of the personal information involved in this application in an appropriate manner in accordance with relevant laws and regulations, and user authorization should be obtained.

[0020] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0021] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can also refer to the internal connection of two components; and they can refer to a wireless connection or a wired connection. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0022] This application provides a circuit that simultaneously implements soft start and overvoltage protection, such as... Figure 1 As shown, it includes: a braking chopper control circuit 1, a soft start circuit 2, an overvoltage protection circuit 3, and a controller 4.

[0023] The first terminal of the soft-start circuit 2 is connected to the first DC power supply, and the second terminal of the soft-start circuit 2 is connected to the first terminal of the DC bus capacitor. The second terminal of the DC bus capacitor is grounded. The grounding connection is as follows: Figure 1 Not shown in the image.

[0024] Specifically, the first DC power supply is a DC power supply output after rectification of three-phase AC power.

[0025] When the voltage across the DC bus capacitor exceeds a first preset value, the controller 4 generates a first control signal and sends a drive signal to the inverter circuit 5 of the motor; when the voltage exceeds a second preset value, it generates a second control signal and stops sending drive signals to the inverter circuit 5.

[0026] It should be noted that the first preset value is the voltage at which the soft start is completed. The first preset value can be set to 90% of the rated voltage of the DC bus. A preset time period can also be set. During the preset time period, if the voltage across the DC bus capacitor is maintained above the first preset value, it indicates that the circuit has completed the soft start. The controller 4 generates a first control signal and sends a drive signal to the inverter circuit 5. The inverter circuit 5 converts the DC power from the first DC power supply into frequency- and voltage-adjustable three-phase AC power, driving the motor to operate normally.

[0027] The second preset value is a preset threshold voltage representing the voltage of the first DC power supply when it is too high. When the voltage across the DC bus capacitor exceeds the second preset value, it means that the voltage of the first DC power supply is too high, and the overvoltage protection circuit needs to be activated to discharge the DC bus voltage. At the same time, in order to prevent damage to the device, the drive signal sent to the inverter circuit 5 needs to be stopped.

[0028] The first control signal is used to short-circuit the soft-start circuit 2; for example, the first control signal can be a high level. The second control signal is used to enable the overvoltage protection circuit 3; for example, the second control signal can be a high level.

[0029] like Figure 1 As shown, the first terminal of the braking chopper control circuit 1 is connected to the first output terminal of the controller 4, the second terminal of the braking chopper control circuit 1 is connected to the second DC power supply, the third terminal of the braking chopper control circuit 1 is connected to the first terminal of the soft start circuit 2, and the fourth terminal of the braking chopper control circuit 1 is connected to the first terminal of the DC bus capacitor, the soft start circuit 2, and the inverter circuit 5 of the motor, respectively. The braking chopper control circuit 1 receives the first control signal sent by the controller 4 and short-circuits the soft start circuit 2 according to the first control signal.

[0030] In this embodiment, when the first DC power supply starts supplying power to the motor through the inverter circuit 5, the soft-start circuit is activated to suppress the surge current generated during the charging of the DC bus capacitor. When the controller 4 detects that the voltage across the DC bus capacitor rises to a first preset value, the controller 4 outputs a first control signal from its first output terminal to the braking chopper control circuit 1. The braking chopper control circuit 1 responds to the first control signal by short-circuiting the soft-start circuit 2, removing the restriction of the soft-start circuit 2 on the main circuit. Simultaneously, the controller 4 outputs a drive signal to the inverter circuit 5, which converts the DC power from the first DC power supply into frequency- and voltage-adjustable three-phase AC power to drive the motor to operate normally.

[0031] like Figure 1 As shown, the first terminal of the overvoltage protection circuit 3 is connected to the second output terminal of the controller 4, the second terminal of the overvoltage protection circuit 3 is connected to the soft-start circuit 2, and the third terminal of the overvoltage protection circuit 3 is grounded. The overvoltage protection circuit 3 receives the second control signal sent by the controller 4, and discharges the energy in the soft-start circuit 2 according to the second control signal. The grounding connection is as follows: Figure 1 Not shown in the image.

[0032] In this embodiment, under conditions such as motor deceleration feedback energy and abnormal load, the voltage of the first DC power supply continuously rises. When the controller 4 determines that the voltage across the DC bus capacitor exceeds the second preset value based on the collected voltage, the controller 4 outputs a second control signal from the second output terminal to the overvoltage protection circuit 3. The overvoltage protection circuit 3 responds to the second control signal and activates the protection logic, forming an energy discharge path based on the soft-start circuit 2 to release excess electrical energy on the DC bus and suppress the continuous rise of the DC bus voltage. At the same time, the controller 4 cuts off the drive signal sent to the inverter circuit 5, and the inverter circuit 5 stops power conversion to prevent the inverter circuit 5, DC bus capacitor, and other components from being damaged by excessive voltage. When the voltage across the DC bus capacitor falls back to the normal operating voltage range, the overvoltage protection circuit 3 is turned off, and the inverter circuit 5 enters the normal operating mode. The power switching devices inside the inverter circuit 5 are switched on and off in an orderly manner, converting to frequency- and voltage-adjustable three-phase AC power to drive the motor to operate normally.

[0033] This implementation reuses the soft-start circuit, which can both suppress power-on surges and perform energy discharge when the DC bus is overvoltaged. It eliminates the need to configure separate soft-start branches and overvoltage energy discharge branches, reducing hardware redundancy and effectively lowering the overall BOM material cost.

[0034] In one alternative implementation, such as Figure 2 As shown, the soft-start circuit 2 includes a first resistor R1 and a first diode D1. The first end of the first resistor R1 is connected to the first DC power supply, the second end of the first resistor R1 is connected to the anode of the first diode D1 and the second end of the overvoltage protection circuit 3, and the cathode of the first diode D1 is connected to the first end of the DC bus capacitor DC-link, the fourth end of the braking chopper control circuit 1, and the inverter circuit 5.

[0035] Specifically, when the first DC power supply VP starts supplying power to the motor through the inverter circuit 5, the first DC power supply VP charges the DC bus capacitor DC-link through the first resistor R1 and the first diode D1. When the controller 4 detects that the voltage across the DC bus capacitor DC-link has risen to a first preset value, the controller 4 outputs a first control signal from the first output terminal to the braking chopper control circuit 1. The braking chopper control circuit 1 responds to the first control signal by short-circuiting the first resistor R1 and the first diode D1, removing the restriction of the first resistor R1 and the first diode D1 on the main circuit, and eliminating the continuous power consumption of the first resistor R1.

[0036] In one alternative implementation, such as Figure 2As shown, the overvoltage protection circuit includes a first power switch Q1. The control terminal of the first power switch Q1 is connected to the second output terminal of the controller 4. The first terminal of the first power switch Q1 is connected to the second terminal of the first resistor R1 and the anode of the first diode D1, respectively. The second terminal of the first power switch Q1 is grounded.

[0037] Specifically, when the controller 4 determines that the voltage across the DC bus capacitor DC-link exceeds the second preset value based on the collected voltage, the controller 4 outputs a high level from the second output terminal BK to the gate of the first power switch Q1, causing the first power switch Q1 to conduct. The overvoltage protection circuit 3 responds to the second control signal, conducts the first power switch Q1, and forms an energy discharge path based on the first resistor R1 in the soft-start circuit 2, releasing excess electrical energy and suppressing the continuous rise of the voltage of the first DC power supply VP. When the voltage across the DC bus capacitor DC-link falls back to the normal operating voltage range, the first power switch Q1 is turned off, that is, the controller 4 outputs a low level to the gate of the first power switch Q1, the inverter circuit 5 enters the normal operating mode, and the power switching devices inside the inverter circuit 5 are turned on and off in an orderly manner, converting to frequency- and voltage-adjustable three-phase AC power to drive the motor to operate normally.

[0038] In one alternative implementation, such as Figure 2 As shown, the braking chopper control circuit 1 includes: a second power switch Q2 and a first relay K1.

[0039] The first relay K1 includes a coil and a normally open contact. The first end of the normally open contact is connected to the first end of the first resistor R1, and the second end of the normally open contact is connected to the first end of the DC bus capacitor DC-link, the cathode of the first diode D1, and the inverter circuit 5, respectively. The first end of the coil is connected to the first end of the second power switch Q2, and the second end of the coil is connected to the second DC power supply VCC.

[0040] The control terminal of the second power switch Q2 is connected to the first output terminal of the controller 4, and the second terminal of the second power switch Q2 is grounded.

[0041] Specifically, after the controller 4 detects that the voltage across the DC-link capacitor has risen to a first preset value, the controller 4 outputs a first control signal from its first output terminal to the braking chopper control circuit 1. The braking chopper control circuit 1 responds to the first control signal by turning on the second power switch Q2, energizing the coil of the first relay K1, closing its normally open contact, and thus short-circuiting the first resistor R1 and the first diode D1 in the soft-start circuit 2, removing the restriction of the soft-start circuit 2 on the main circuit. Simultaneously, the first DC power supply VP supplies power to the motor's inverter circuit 5 through the normally open contact of the first relay K1.

[0042] Furthermore, such as Figure 2 As shown, the braking chopper control circuit 1 also includes: a second resistor R2, a third resistor R3, a first capacitor C1, and a second diode D2.

[0043] The first end of the second resistor R2 is connected to the first output terminal of the controller 4, and the second end of the second resistor R2 is connected to the first end of the third resistor R3 and the first end of the second power switch Q2.

[0044] The second terminal of the third resistor R3 is grounded.

[0045] The first capacitor C1 is connected in parallel between the control terminal and the second terminal of the second power switch Q2.

[0046] Specifically, when controller 4 detects that the voltage across the DC-link capacitor rises to the first preset value, controller 4 outputs a high level from its first output terminal RE to the first terminal of the second resistor R2, thereby turning on the second power switch Q2. This energizes the coil of the first relay K1, closing its normally open contact and short-circuiting the first resistor R1 and the first diode D1 in the soft-start circuit 2, removing the restriction of the soft-start circuit 2 on the main circuit. The second resistor R2 is a current-limiting resistor, used to limit the circuit current and prevent excessive inrush current from damaging the devices. The third resistor R3 is a pull-down resistor, used to pull the gate potential of the second power switch Q2 to GND when the first output terminal RE of controller 4 does not output the first control signal, ensuring reliable shutdown of the second power switch Q2. The first capacitor C1 is a voltage-regulating capacitor, used to suppress spike interference and prevent the second power switch Q2 from being mis-turned on.

[0047] The anode of the second diode D2 is connected to the first terminal of the coil, and the cathode of the second diode D2 is connected to the second terminal of the coil. The second diode D2 is connected in parallel across the coil of the first relay K1. When the coil is de-energized, the reverse induced electromotive force is released through the second diode D2, preventing the second power switch Q2 from being damaged.

[0048] In one alternative implementation, such as Figure 2 As shown, the circuit that simultaneously achieves soft start and overvoltage protection also includes: a voltage acquisition circuit 6, the first terminal of which is connected to the first terminal of the DC bus capacitor DC-link, the second terminal of which is connected to the first input terminal of the controller 4, and the third terminal of which is grounded.

[0049] Specifically, the voltage acquisition circuit 6 includes a fourth resistor R4 and a fifth resistor R5.

[0050] The first end of the fourth resistor R4 is connected to the first end of the DC bus capacitor DC-link. The second end of the fourth resistor R4 is connected to the first end of the fifth resistor R5 and the first input terminal of the controller 4. The second end of the fifth resistor R5 is grounded.

[0051] In this embodiment, the fourth resistor R4 and the fifth resistor R5 are connected in series to divide the voltage. The attenuated voltage signal obtained at the second end of the fourth resistor R4 is sent to the controller 4. The controller 4 collects the voltage across the DC-link of the DC bus capacitor based on the first input terminal ADC-VP, determines whether it exceeds the second preset value, and then decides whether to activate the overvoltage protection circuit.

[0052] In one alternative implementation, such as Figure 2 As shown, the circuit that simultaneously implements soft start and overvoltage protection also includes a rectifier module 7. The input terminal of the rectifier module 7 is connected to the three-phase AC bus, the first output terminal of the rectifier module 7 is connected to the first terminal of the soft start circuit 2, and the second output terminal of the rectifier module 7 is grounded. The rectifier module 7 is used to rectify the AC power on the three-phase AC bus into DC power to provide the operating voltage for the inverter circuit 5.

[0053] Specifically, rectifier module 7 can be as follows: Figure 2 The circuit structure shown can also be any other circuit structure that can rectify three-phase AC power into DC power. This invention does not limit the specific structure of the rectifier module 7.

[0054] Furthermore, the circuit that simultaneously achieves soft start and overvoltage protection also includes an inverter circuit 5. The first input terminal of the inverter circuit 5 is connected to the fourth terminal of the braking chopper control circuit 1, the PWM input terminal of the inverter circuit 5 is connected to the PWM output terminal of the controller 4, and the output terminal of the inverter circuit 5 is connected to the motor; the inverter circuit 5 is used to provide three-phase AC power to the motor.

[0055] like Figure 2 The inverter circuit 5 shown can be as follows: Figure 2 The three-phase full-bridge inverter topology shown can also be any other circuit structure that can provide three-phase AC power to the motor. This invention does not limit the specific structure of the inverter circuit 5.

[0056] It should be noted that the first power switch Q1, the first diode D1, the inverter circuit 5, and the rectifier module 7 can be integrated into the same power integrated module. In practical applications, existing high-performance integrated modules with the above-mentioned components and circuits can be directly selected to build the circuit of this invention.

[0057] In addition, the inverter circuit also includes a thermistor R12. One end of the thermistor R12 is connected to a 3.3V voltage, and the other end is connected to the third input port ADC_NTC of the controller 4 and one end of the eleventh resistor R11. The other end of the eleventh resistor R11 is grounded. The higher the temperature, the lower the resistance of the thermistor R12, and the ADC_NTC voltage changes accordingly. The controller 4 implements overheat protection by reading the voltage.

[0058] In one alternative implementation, such as Figure 2 As shown, the circuit that simultaneously achieves soft start and overvoltage protection also includes a current acquisition circuit, which includes a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, and a ninth resistor R9.

[0059] The first terminal of the sixth resistor R6 is connected to the first acquisition terminal of the inverter circuit 5, the first terminal of the seventh resistor R7 is connected to the second acquisition terminal of the inverter circuit 5, and the first terminal of the eighth resistor R8 is connected to the third acquisition terminal of the inverter circuit 5. The second terminals of the sixth resistor R6, the seventh resistor R7, and the eighth resistor R8 are all connected to the first terminal of the ninth resistor R9, and the second terminal of the ninth resistor R9 is grounded.

[0060] In a specific circuit, the first terminals of the sixth resistor R6, the seventh resistor R7, the eighth resistor R8, and the ninth resistor R9 can be connected to the feedback input terminal of the controller 4. The current acquisition circuit feeds back the acquired current to the controller 4 to adjust the PWM signal output by the controller 4, that is, to adjust the PWM output of the controller 4's PWM output terminals (DR_UH, DR_UL, DR_VH, DR_VL, DR_WH, and DR_WL), thereby controlling the motor's start / stop, direction, speed, etc. The connection relationship between the current acquisition circuit and the controller 4 is as follows: Figure 2 Not shown in the image.

[0061] In one alternative implementation, such as Figure 2 As shown, the circuit that simultaneously implements soft start and overvoltage protection also includes a temperature detection circuit, which detects the temperature of the first resistor R1 and transmits it to the controller 4. The controller 4 adjusts the second control signal based on the temperature of the first resistor R1.

[0062] Specifically, the temperature detection circuit includes a temperature sensor NTC_Seasor and a tenth resistor R10. The first end of the tenth resistor R10 is connected to the second input terminal ADC_NTC1 of the controller 4 and the temperature sensor NTC_Seasor, respectively, and the first end of the tenth resistor R10 is grounded.

[0063] By detecting the temperature of the temperature sensor on the first resistor R1, the on and off states of the first power switch Q1 are adjusted in real time. If the temperature of the first resistor R1 is detected to be too high, the first power switch Q1 is turned off to prevent the components in the circuit from overheating and being damaged.

[0064] Although embodiments of this application have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of this application, and all such modifications and variations fall within the scope defined by the appended claims.

Claims

1. A circuit that simultaneously achieves soft start and overvoltage protection, characterized in that, The circuit includes: a braking chopper control circuit, a soft-start circuit, an overvoltage protection circuit, and a controller, wherein... The first terminal of the soft-start circuit is connected to the first DC power supply, the second terminal of the soft-start circuit is connected to the first terminal of the DC bus capacitor, and the second terminal of the DC bus capacitor is grounded. When the voltage across the DC bus capacitor exceeds a first preset value, the controller generates a first control signal and sends a drive signal to the inverter circuit of the motor; when the voltage exceeds a second preset value, it generates a second control signal and stops sending drive signals to the inverter circuit. The first terminal of the braking chopper control circuit is connected to the first output terminal of the controller, the second terminal of the braking chopper control circuit is connected to the second DC power supply, the third terminal of the braking chopper control circuit is connected to the first terminal of the soft start circuit, and the fourth terminal of the braking chopper control circuit is connected to the first terminal of the DC bus capacitor, the soft start circuit, and the inverter circuit respectively; the braking chopper control circuit receives the first control signal sent by the controller and short-circuits the soft start circuit according to the first control signal; The first terminal of the overvoltage protection circuit is connected to the second output terminal of the controller, the second terminal of the overvoltage protection circuit is connected to the soft-start circuit, and the third terminal of the overvoltage protection circuit is grounded; the overvoltage protection circuit receives the second control signal sent by the controller, and the overvoltage protection circuit releases the energy in the soft-start circuit according to the second control signal.

2. The circuit that simultaneously achieves soft start and overvoltage protection according to claim 1, characterized in that, The soft-start circuit includes: a first resistor and a first diode, wherein, The first end of the first resistor is connected to the first DC power supply, the second end of the first resistor is connected to the anode of the first diode and the second end of the overvoltage protection circuit, and the cathode of the first diode is connected to the first end of the DC bus capacitor, the fourth end of the braking chopper control circuit and the inverter circuit.

3. The circuit that simultaneously achieves soft start and overvoltage protection according to claim 2, characterized in that, The overvoltage protection circuit includes a first power switch transistor, the control terminal of the first power switch transistor is connected to the second output terminal of the controller, the first terminal of the first power switch transistor is connected to the second terminal of the first resistor and the anode of the first diode, and the second terminal of the first power switch transistor is grounded.

4. The circuit that simultaneously achieves soft start and overvoltage protection according to claim 2, characterized in that, The braking chopper control circuit includes: a second power switch and a first relay, wherein... The first relay includes a coil and a normally open contact. The first end of the normally open contact is connected to the first end of the first resistor, and the second end of the normally open contact is connected to the first end of the DC bus capacitor, the cathode of the first diode, and the inverter circuit, respectively. The first end of the coil is connected to the first end of the second power switch, and the second end of the coil is connected to the second DC power supply. The control terminal of the second power switch is connected to the first output terminal of the controller, and the second terminal of the second power switch is grounded.

5. The circuit that simultaneously achieves soft start and overvoltage protection according to claim 4, characterized in that, The braking chopper control circuit further includes: a second resistor, a third resistor, a first capacitor, and a second diode, wherein, The first end of the second resistor is connected to the first output terminal of the controller, and the second end of the second resistor is connected to the first end of the third resistor and the first end of the second power switch, respectively. The second terminal of the third resistor is grounded; The first capacitor is connected in parallel between the control terminal and the second terminal of the second power switch. The anode of the second diode is connected to the first end of the coil, and the cathode of the second diode is connected to the second end of the coil.

6. The circuit that simultaneously achieves soft start and overvoltage protection according to claim 2, characterized in that, The circuit further includes a temperature detection circuit, which detects the temperature of the first resistor and transmits it to the controller, which adjusts the second control signal based on the temperature of the first resistor.

7. The circuit that simultaneously achieves soft start and overvoltage protection according to claim 1, characterized in that, The circuit further includes a voltage acquisition circuit, the first terminal of which is connected to the first terminal of the DC bus capacitor, the second terminal of which is connected to the first input terminal of the controller, and the third terminal of which is grounded.

8. The circuit that simultaneously achieves soft start and overvoltage protection according to claim 7, characterized in that, The voltage acquisition circuit includes a fourth resistor and a fifth resistor; The first end of the fourth resistor is connected to the first end of the DC bus capacitor, the second end of the fourth resistor is connected to the first end of the fifth resistor and the first input terminal of the controller, and the second end of the fifth resistor is grounded.

9. The circuit that simultaneously achieves soft start and overvoltage protection according to claim 2, characterized in that, The circuit further includes: a rectifier module, the input terminal of which is connected to the three-phase AC bus, the first output terminal of which is connected to the first terminal of the soft-start circuit, and the second output terminal of which is grounded; the rectifier module is used to rectify the AC power on the three-phase AC bus into DC power to provide operating voltage for the inverter circuit.

10. The circuit that simultaneously achieves soft start and overvoltage protection according to claim 2, characterized in that, The circuit also includes: an inverter circuit; The first input terminal of the inverter circuit is connected to the fourth terminal of the braking chopper control circuit, the PWM input terminal of the inverter circuit is connected to the PWM output terminal of the controller, and the output terminal of the inverter circuit is connected to the motor; the inverter circuit is used to provide three-phase AC power to the motor.

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