A method and system for charging a bootstrap capacitor of an electric compressor controller

Abstract

The embodiment of the application provides a kind of electric compressor controller bootstrap capacitor charging method and system, comprising the following steps: S1: according to the resistance capacitance value of bootstrap charging circuit, the time required to fill bootstrap capacitor is calculated;S2: the minimum duty ratio is set based on the drive control frequency of the controller, the bootstrap capacitor single switch charging duration is calculated;S3: the working time of the low-voltage side switch tube in three single-phase half-bridge units is calculated;S4: the bootstrap capacitor of the corresponding single-phase half-bridge unit is charged to the required voltage value.Control relates to the field of new energy vehicle electric compressor.The time required to fill bootstrap capacitor is accurately calculated according to the resistance capacitance value of bootstrap charging circuit, which improves the charging efficiency and the stability of high-voltage side switch tube drive, especially suitable for reliable operation of new energy truck in frequent start-stop and high-load scenarios.

Description

Technical Field

[0001] This invention relates to the field of electric compressors for new energy vehicles, specifically to a method and system for charging the bootstrap capacitor of an electric compressor controller. Background Technology

[0002] With increasing environmental awareness and the transformation of the energy structure, new energy vehicles, especially new energy trucks, are being used more and more widely in the logistics and transportation sector. New energy trucks typically employ electric drive systems, using batteries as the primary energy source to replace traditional combustion engines, thereby achieving zero emissions and high-efficiency operation. In the air conditioning or auxiliary systems of new energy trucks, the electric compressor, as a key component, provides compressed air or refrigeration cycles. Its controller is responsible for precisely regulating the motor speed and power output to adapt to the vehicle's needs under different loads and environmental conditions. However, existing electric compressor controllers mostly use bootstrap circuits to drive the high-voltage side switching transistors. This circuit relies on the charging process of the bootstrap capacitor to maintain a stable gate voltage.

[0003] In existing technologies, bootstrap capacitor charging is typically achieved through a simple resistor-capacitor network. The charging time relies on empirically set circuit parameters without considering dynamic factors such as drive control frequency and minimum duty cycle. This can lead to insufficient charging of the bootstrap capacitor during the start-up or low-speed operation phases of new energy trucks, causing high-voltage side switch failure, increased risk of bridge arm shoot-through, and even motor vibration, reduced efficiency, or system malfunctions. These problems are particularly amplified in high-load transportation scenarios for new energy trucks, such as long-distance logistics or urban delivery, where frequent start-stop operations and complex road conditions further amplify these issues, impacting vehicle reliability and energy efficiency. Furthermore, existing charging methods often neglect the coordinated control of single-phase half-bridge units, resulting in three-phase system imbalance, increased energy consumption, and shortened component lifespan.

[0004] To address the aforementioned issues, a method for optimizing bootstrap capacitor charging is needed. This method should be able to accurately calculate the charging time based on the resistor and capacitor values, set the minimum duty cycle in conjunction with the drive frequency, and calculate the operating time of the low-voltage side switching transistor. This ensures that the bootstrap capacitor is charged efficiently and safely to the required voltage value. This method is particularly suitable for new energy freight vehicles, improving the starting performance of the electric compressor controller and the overall system stability. Summary of the Invention

[0005] According to embodiments of the present invention, a method and system for charging the bootstrap capacitor of an electric compressor controller are provided. This addresses the technical problems existing in the background art described above.

[0006] In a first aspect of the invention, a method for charging a bootstrap capacitor in an electric compressor controller is provided.

[0007] Includes the following steps:

[0008] S1: Calculate the time required to fully charge the bootstrap capacitor based on the resistance and capacitance values ​​of the bootstrap charging circuit.

[0009] S2: Based on the drive control frequency of the controller, set the minimum duty cycle and calculate the single switching charging time of the bootstrap capacitor;

[0010] S3: Calculate the operating time of the low-voltage side switching transistors in the three single-phase half-bridge units;

[0011] S4: Control the bootstrap capacitor of the corresponding single-phase half-bridge unit to charge to the required voltage value.

[0012] Preferably, in step S1, the time required to fully charge the bootstrap capacitor is five times the value of the resistor and capacitor.

[0013] In step S2, the duration of a single switching charge is equal to the minimum duty cycle divided by the drive control frequency.

[0014] In step S3, the number of pulses of the low-voltage side switch in the single-phase half-bridge unit is calculated based on the ratio of the time required to fully charge the bootstrap capacitor to the duration of a single switch charging. The required working time is obtained by dividing the number of pulses by the minimum duty cycle, and twice the value of the required working time is taken as the final working time of the low-voltage side switch in the single-phase half-bridge unit.

[0015] In step S4, the low-voltage side switch tubes in the corresponding single-phase half-bridge unit are controlled to turn on in turn for two-thirds of the required working time according to the minimum duty cycle, and the bootstrap capacitor in the corresponding single-phase half-bridge unit is charged to the required voltage value through three turns of conduction.

[0016] Preferably, the method further includes a fault detection step: charging the bootstrap capacitor after acquiring the three-phase line voltage UVDC;

[0017] Compare the UVDC voltage with the bus voltage sampling value. If the difference between the two is less than 5%, it is determined that there is a short circuit fault in the high voltage side circuit of the half-bridge unit or the line voltage exceeds the range.

[0018] If the UVDC voltage is less than the minimum preset value, it is determined that a short circuit fault has occurred in the low-voltage side circuit of the half-bridge unit.

[0019] Based on the judgment result, the bootstrap capacitor charging program is interrupted and a fault signal is issued.

[0020] Preferably, the fault detection step is implemented by a detection circuit, which includes a voltage divider resistor and an operational amplifier chip;

[0021] The voltage divider resistors are used to sample the phase line voltage;

[0022] The operational amplifier chip is used to amplify the sampling voltage;

[0023] The method also includes the step of monitoring and starting the load motor: after the bootstrap capacitor is charged, a small PWM pulse is applied to monitor the shaft mobility response of the load motor. If the response exceeds the threshold, an electromechanical connection command is sent and a confirmation signal is sent. After confirmation, the high-voltage bus is closed, and the duty cycle is gradually increased to monitor the changes in shaft speed, phase current and bus voltage. If there is no abnormality, normal operation is started; otherwise, the operation is interrupted and an abnormal signal is sent.

[0024] In a second aspect of the invention, a bootstrap capacitor charging system for an electric compressor controller is provided.

[0025] It includes a low-voltage power supply, a drive unit, a load motor, three single-phase half-bridge units, and a control unit, wherein the drive unit includes a bootstrap charging circuit, and the control unit includes a detection circuit and a control circuit.

[0026] The low-voltage power supply positive terminal is connected to the input of the bootstrap charging circuit to provide positive charge for charging the bootstrap capacitor.

[0027] The negative terminal of the bootstrap charging circuit is connected to the low-voltage side switch of the three single-phase half-bridge units to control the charging rate of the bootstrap capacitor.

[0028] Preferably, the bootstrap charging circuit includes an anti-reverse-feedback diode, a charging resistor, and a bootstrap capacitor;

[0029] Each of the single-phase half-bridge units includes a high-voltage side switch and a low-voltage side switch, wherein the low-voltage power supply positive terminal of the low-voltage power supply is connected to the bootstrap capacitor through the anti-reverse-feedback diode and the charging resistor, and the bootstrap capacitor is used to provide the gate drive voltage for the high-voltage side switch.

[0030] Preferably, the detection circuit is connected to the low-voltage side switch transistor and is used to collect voltage jumps after the low-voltage side switch transistor is controlled by a PWM square wave, and to determine the bridge arm shoot-through risk by the maximum voltage value and its frequency.

[0031] The detection circuit is capable of receiving fault detection input signals.

[0032] Preferably, the charging resistor is used to limit the charging current to avoid current spikes, while the value of the charging resistor is optimized by the bootstrap capacitor charging method so as not to limit the minimum duty cycle of the motor control algorithm.

[0033] Preferably, the drive unit includes a driver and a positive terminal for the high-voltage side switch control signal, a negative terminal for the high-voltage side switch control signal, and a positive terminal for the low-voltage side switch control signal disposed on the driver;

[0034] The positive and negative terminals of the high-voltage side switch control signal are connected to the high-voltage side switch.

[0035] Preferably, the detection circuit is also used to collect the three-phase line voltage UVDC after the high voltage is applied, and to determine the high-voltage side or low-voltage side short circuit fault based on the comparison between the UVDC voltage and the bus voltage sampling value and the comparison with the lowest preset value.

[0036] One or more technical solutions provided in this application have at least the following technical effects or advantages:

[0037] This invention provides a method and system for charging the bootstrap capacitor of an electric compressor controller. By accurately calculating the time required to fully charge the bootstrap capacitor based on the resistance and capacitance values ​​of the bootstrap charging circuit, and by combining the minimum duty cycle setting of the drive control frequency to calculate the single charging duration and the working time of the low-voltage side switching transistor, the optimized charging process of the bootstrap capacitor is achieved. This avoids the problems of insufficient or overcharging caused by traditional experience-based settings, improves charging efficiency and the stability of the high-voltage side switching transistor drive, and is especially suitable for the reliable operation of new energy trucks in frequent start-stop and high-load scenarios.

[0038] This invention introduces a fault detection step, which collects the three-phase line voltage and compares it with the bus voltage to determine whether there is a short circuit fault on the high-voltage side or the low-voltage side, and then performs self-bootstrapping charging. It also monitors the risk of bridge arm shoot-through, which effectively reduces the probability of system failure, enhances the safety and lifespan of the electric compressor controller, and reduces the potential risks and maintenance costs of the air conditioning system or auxiliary system of new energy trucks.

[0039] It should be understood that the description in the Summary of the Invention is not intended to limit the key or essential features of the embodiments of the present invention, nor is it intended to restrict the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0040] The above and other features, advantages, and aspects of the various embodiments of the present invention will become more apparent from the accompanying drawings and the following detailed description. In the drawings, the same or similar reference numerals denote the same or similar elements, wherein:

[0041] Figure 1 A flowchart of a bootstrap capacitor charging method for an electric compressor controller according to an embodiment of the present invention is shown;

[0042] Figure 2A charging schematic diagram of a bootstrap capacitor charging method for an electric compressor controller according to an embodiment of the present invention is shown;

[0043] Figure 3 Another charging schematic diagram of the bootstrap capacitor charging method for an electric compressor controller according to an embodiment of the present invention is shown;

[0044] Figure 4 A schematic diagram of a detection circuit according to an embodiment of the present invention is shown;

[0045] Figure 5 A schematic diagram illustrating an application scenario of a bootstrap circuit according to an embodiment of the present invention is shown;

[0046] Figure 6 A schematic diagram of the operation of a bootstrap circuit according to an embodiment of the present invention is shown;

[0047] Figure 7 A three-dimensional connection structure diagram of an electric compressor controller bootstrap capacitor charging system according to an embodiment of the present invention is shown;

[0048] Figure 8 An exploded view of an electric compressor controller bootstrap capacitor charging system according to an embodiment of the present invention is shown;

[0049] Figure 9 A schematic diagram of the connection structure of the mobile module and monitoring component of the electric compressor controller bootstrap capacitor charging system according to an embodiment of the present invention is shown.

[0050] Figure 10 A schematic diagram of the connection structure of the mobile module and monitoring component of the electric compressor controller bootstrap capacitor charging system according to an embodiment of the present invention is shown from another perspective.

[0051] Figure 11 An exploded view of the moving module and monitoring components of the electric compressor controller bootstrap capacitor charging system according to an embodiment of the present invention is shown;

[0052] Figure 12 A schematic diagram of the planar connection structure of the mobile module of the electric compressor controller bootstrap capacitor charging system according to an embodiment of the present invention is shown.

[0053] Figure 13 A schematic diagram of a partial connection structure of the snap-fit ​​assembly of an electric compressor controller bootstrap capacitor charging system according to an embodiment of the present invention is shown.

[0054] Figure 14 A schematic diagram of the connection structure of the outer ring, pawl, and ratchet of the electric compressor controller bootstrap capacitor charging system according to an embodiment of the present invention is shown.

[0055] The attached figures are labeled as follows:

[0056] 1-Low-voltage power supply, 10-Charging resistor, 101-Low-voltage power supply positive terminal, 11-Operational amplifier chip, 12-Voltage divider resistor, 13-High-voltage side switch transistor, 14-Low-voltage side switch transistor, 15-Bootstrap capacitor, 16-Electric compressor controller tester, 2-Drive unit, 201-High-voltage side switch transistor control signal positive terminal, 202-High-voltage side switch transistor control signal negative terminal, 203-Low-voltage side switch transistor control signal positive terminal, 204-Driver, 3-Single-phase half-bridge unit, 4-Control unit, 401-Fault detection input signal, 402-Detection circuit, 403-Control circuit, 5-Load motor, 6-Anti-reverse current protection 7-Electrical tube, 7-Snap-fit ​​assembly, 701-First connecting shaft, 702-Claw, 703-Claw slot, 704-Base, 705-Connecting rod, 706-Second connecting shaft, 707-First protrusion, 708-Second protrusion, 709-Spring, 8-Moving module, 801-Second gear ring, 802-Second gear, 803-Frame, 804-Reciprocating screw, 805-Sliding component, 806-Limiting rod, 807-Connecting component, 808-Outer ring, 809-Pawl, 810-Ratchet, 811-Shaft, 812-Torsion spring, 9-Monitoring assembly, 901-First gear ring, 902-First gear, 903-Encoder. Detailed Implementation

[0057] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0058] Furthermore, the term "and / or" in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0059] like Figures 1 to 3 As shown, the self-bootstrapping capacitor charging method for the electric compressor controller includes the following steps:

[0060] S1: Calculate the time required to fully charge the bootstrap capacitor 15 based on the resistance value R and capacitance value C of the bootstrap charging circuit. The time required to fully charge the bootstrap capacitor 15 is 5 times the product of the resistance value R and the capacitance value C, i.e., 5×R×C. This time corresponds to the bootstrap capacitor 15 being charged to approximately 99.3% of its rated voltage to ensure full charging.

[0061] S2: Set the minimum duty cycle D-min based on the controller's drive control frequency f, where D-min is the minimum duty cycle value to ensure the safe conduction of the switch transistor; then, calculate the charging duration of the bootstrap capacitor 15 during a single switch conduction, where the charging duration is equal to D-min / f, and this duration represents the time that the low-voltage side switch transistor 14 is turned on in each drive cycle;

[0062] S3: Based on the ratio of the time required to fully charge the bootstrap capacitor 15 calculated in step S1 to the single-cycle charging time calculated in step S2, calculate the number of pulses N required for the low-voltage side switch transistor 14 in the corresponding single-phase half-bridge unit 3, where N is equal to the ratio after rounding up to ensure sufficient charging pulses; then, calculate the total on-time required for the low-voltage side switch transistor 14 based on the number of pulses N and the minimum duty cycle D-min, where the total on-time is equal to N / D-min; to provide a safety margin, twice the total on-time is taken as the final operating time of the low-voltage side switch transistor 14;

[0063] S4: Control the low-voltage side switch tube 14 in the corresponding single-phase half-bridge unit 3 to conduct in turn according to the minimum duty cycle D-min. Each conduction lasts for two-thirds of the final working time of the low-voltage side switch tube 14, that is, the conduction time is (2 / 3) times the final working time. Through three conduction cycles (corresponding to each phase in the three-phase half-bridge structure), the bootstrap capacitor 15 in the corresponding single-phase half-bridge unit 3 is gradually charged to the required voltage value. This process ensures that the bootstrap capacitor 15 reaches a stable working voltage before the electric compressor controller starts, thereby avoiding the failure of the high-voltage side switch tube drive.

[0064] In this embodiment, the method further includes a fault detection step, which is a fault detection step performed after charging the bootstrap capacitor 15. Specifically, it includes the following sub-steps:

[0065] The three-phase line voltage UVDC is collected, where UVDC represents the voltage values ​​of phase U, phase V, and phase W relative to the DC bus;

[0066] The collected UVDC voltage is compared with the bus voltage sampling value. If the difference between the UVDC voltage and the bus voltage sampling value is less than 5%, it is determined that the high-voltage side circuit of the corresponding single-phase half-bridge unit 3 has a short circuit fault or the line voltage exceeds the preset range.

[0067] If the UVDC voltage is less than the minimum preset value (which is set based on system design parameters, such as 10% of the bus voltage), then it is determined that a short circuit fault has occurred in the low-voltage side circuit of the corresponding single-phase half-bridge unit 3.

[0068] Based on the above judgment results, the charging program of the bootstrap capacitor 15 is interrupted, and a corresponding fault signal is issued to notify the controller to stop operation and troubleshoot the fault.

[0069] The fault detection step is implemented through a detection circuit 402, which includes a voltage divider resistor 12 and an operational amplifier chip 11. The voltage divider resistor 12 is connected between the phase line and ground to sample the phase line voltage and reduce the voltage level to match the input range of subsequent circuits. The operational amplifier chip 11 is connected to the output terminal of the voltage divider resistor 12 to amplify the sampled voltage signal to improve signal accuracy and anti-interference capability, and transmits the amplified signal to the microprocessor of the controller for comparison and analysis.

[0070] In addition, the method also includes the step of monitoring and starting the load motor 5, which is performed after the bootstrap capacitor 15 has finished charging, and specifically includes the following sub-steps:

[0071] Apply a small PWM pulse (e.g., a pulse signal with a duty cycle of 5%-10%) to the load motor 5 to monitor the shaft mobility response of the load motor 5, which includes shaft rotation amplitude or vibration feedback;

[0072] If the shaft mobility response exceeds a preset threshold (this threshold is set based on the motor specifications, for example, 50% of the normal rotation amplitude), an electromechanical connection command is sent, and a confirmation signal is waited for. This confirmation signal is generated by a position sensor or feedback circuit to ensure that the motor shaft is correctly connected to the mechanical parts of the compressor.

[0073] After receiving the arrival signal confirmation, it was determined that there was no abnormality in the high-voltage circuit;

[0074] Gradually increase the duty cycle of the PWM pulse (e.g., by increments of 1%-5%), while simultaneously monitoring the changes in shaft speed, phase current, and bus voltage of the load motor 5 in real time.

[0075] If no abnormalities are detected during monitoring (e.g., shaft speed increases steadily, phase current is within the preset range, and bus voltage is stable), the system will enter normal operation mode; otherwise, the startup process will be interrupted and an abnormal signal will be issued to prevent further damage to the equipment.

[0076] like Figures 4 to 14As shown, in addition, according to another embodiment of the present invention, an electric compressor controller bootstrap capacitor charging system is also provided. The system includes a low-voltage power supply 1, a drive unit 2, a load motor 5, three single-phase half-bridge units 3 and a control unit 4, wherein the drive unit 2 includes a bootstrap charging circuit and the control unit 4 includes a detection circuit 402 and a control circuit 403.

[0077] The low-voltage power supply positive terminal 101 of the low-voltage power supply 1 is electrically connected to the input terminal of the bootstrap charging circuit to provide a low-voltage DC power supply to the bootstrap charging circuit, thereby providing a positive charge source for charging the bootstrap capacitor 15.

[0078] The negative terminal of the bootstrap charging circuit is electrically connected to the source or emitter of the low-voltage side switch 14 in the three single-phase half-bridge units 3. It is used to control the charging path of the bootstrap capacitor 15 by turning the low-voltage side switch 14 on and off, thereby adjusting the charging rate of the bootstrap capacitor 15 to prevent current surges or voltage instability caused by excessively fast charging.

[0079] The detection circuit 402 is electrically connected to the gate or electrode of the low-voltage side switching transistor 14. After the low-voltage side switching transistor 14 receives the PWM square wave signal for switching control, it collects the voltage jump signal across the low-voltage side switching transistor 14 in real time and judges the bridge arm shoot-through risk by analyzing the peak value (i.e., the maximum voltage) and its occurrence frequency of the voltage jump. If the maximum voltage exceeds a preset threshold or the frequency is abnormal, it indicates that there is a bridge arm shoot-through risk. The detection circuit 402 is also configured to receive a fault detection input signal 401, which can come from an external sensor or a system self-test module, and is used to trigger additional fault diagnosis processes.

[0080] The control circuit 403 is electrically connected to the detection circuit 402 and is used to receive the judgment result of the detection circuit 402 and generate a control signal accordingly to adjust the operation of the drive unit 2, such as interrupting the charging process or issuing an alarm.

[0081] The three single-phase half-bridge units 3 correspond to phase U, phase V and phase W respectively. Each single-phase half-bridge unit 3 includes a high-voltage side switch tube and a low-voltage side switch tube 14, as well as a bootstrap capacitor 15 connected in parallel with them, for driving the three-phase windings of the load motor 5.

[0082] The load motor 5 is electrically connected to the output terminals of the three single-phase half-bridge units 3, and is used to receive the drive signal after the bootstrap capacitor 15 is fully charged, so as to realize the operation of the electric compressor.

[0083] In actual use, the system first initializes the bootstrap charging process through the control unit 4: the low-voltage power supply 1 supplies power, and the bootstrap charging circuit gradually charges the bootstrap capacitor 15 under the PWM control of the low-voltage side switching transistor 14; at the same time, the detection circuit 402 continuously monitors the voltage signal. If a bridge arm shoot-through risk is detected or a fault detection input signal 401 is received, the control circuit 403 immediately interrupts the charging and protects the system; after charging is completed, the drive unit 2 applies a normal drive signal to the load motor 5 to ensure the safe start and operation of the electric compressor controller.

[0084] In this embodiment, the bootstrap charging circuit includes a reverse-current protection diode 6, a charging resistor 10, and a bootstrap capacitor 15. Each single-phase half-bridge unit 3 includes a high-voltage side switch 13 and a low-voltage side switch 14. The low-voltage positive terminal 101 of the low-voltage power supply 1 is electrically connected to one end of the bootstrap capacitor 15 via the reverse-current protection diode 6 and the charging resistor 10. The other end of the bootstrap capacitor 15 is electrically connected to the output terminal of the single-phase half-bridge unit 3. The bootstrap capacitor 15 is configured to provide a driving voltage to the gate of the high-voltage side switch 13 to ensure that the high-voltage side switch 13 has a sufficient gate voltage when it is turned on. The reverse-current protection diode 6 is used to prevent current from flowing in reverse, thereby protecting the low-voltage power supply 1 from the influence of the high-voltage side circuit. The charging resistor 10 is used to limit the magnitude of the charging current to avoid component damage or electromagnetic interference caused by current spikes during charging. At the same time, the resistance value of the charging resistor 10 is optimized by the bootstrap capacitor charging method so that the resistance value does not limit the minimum duty cycle of the motor control algorithm while meeting the charging rate requirements, thereby ensuring accurate control of the motor under low-speed or low-load conditions.

[0085] The drive unit 2 includes a driver 204, and a high-voltage side switch control signal positive terminal 201, a high-voltage side switch control signal negative terminal 202, and a low-voltage side switch control signal positive terminal 203 disposed on the driver 204. The high-voltage side switch control signal positive terminal 201 and the high-voltage side switch control signal negative terminal 202 are electrically connected to the gate and source (or emitter) of the high-voltage side switch 13, respectively, to provide a floating gate drive signal to the high-voltage side switch 13. The low-voltage side switch control signal positive terminal 203 is electrically connected to the gate of the low-voltage side switch 14 to provide a drive signal for ground reference. The driver 204 is configured to generate a PWM control signal according to the instructions of the control unit 4 to drive the switching action of the high-voltage side switch 13 and the low-voltage side switch 14, thereby realizing the three-phase drive of the load motor 5.

[0086] The detection circuit 402 is also configured to acquire the three-phase line voltage UVDC (i.e., the voltages of phases U, V, and W relative to the DC bus) after the high-voltage bus is powered. Based on the comparison between the acquired UVDC voltage and the bus voltage sample value, and the comparison between the UVDC voltage and a minimum preset value (which is set based on a system safety threshold, for example, 5%-10% of the bus voltage), it determines whether there is a short circuit fault in the high-voltage side or low-voltage side circuit. Specifically, if the difference between the UVDC voltage and the bus voltage sample value is less than a preset percentage (e.g., 5%), it is determined that there is a short circuit fault in the high-voltage side circuit or the line voltage is outside the normal range; if the UVDC voltage is less than the minimum preset value, it is determined that there is a short circuit fault in the low-voltage side circuit. Based on the determination result, the detection circuit 402 sends a fault signal to the control circuit 403 to interrupt subsequent operations and protect the system.

[0087] Control unit 4 is also configured to monitor load motor 5 and execute the startup process: wherein, detection circuit 402 is used to acquire shaft mobility response signals of load motor 5 (e.g., shaft rotation amplitude feedback obtained through position sensor or vibration sensor), as well as changes in shaft speed, phase current, and bus voltage; control circuit 403 is configured to apply a small PWM pulse (e.g., a pulse signal with a duty cycle of 5%-10%) to load motor 5 after the bootstrap capacitor 15 has finished charging, to determine whether shaft mobility is normal (i.e., whether the response is within a preset threshold range); if the determination is normal, an electromechanical connection command is executed (e.g., ...). (For example, the connection between the motor shaft and the mechanical part of the compressor is achieved through a relay or electromagnetic mechanism), and after receiving a connection confirmation signal, it is determined that there is no abnormality in the high-voltage circuit; then, the duty cycle of the PWM pulse is gradually increased (for example, by increments of 1%-5%), while the changes in shaft speed, phase current and bus voltage are monitored in real time through the detection circuit 402; if all parameters are normal during the monitoring process (for example, the shaft speed rises steadily, the phase current does not exceed the rated value, and the bus voltage fluctuation is less than the preset amplitude), then the normal operation mode is entered; otherwise, the start-up process is interrupted and an abnormal signal is issued to prevent equipment damage or safety hazards.

[0088] In actual use, the system is first powered by low-voltage power supply 1, and control unit 4 initializes the bootstrap charging process: the bootstrap charging circuit gradually charges the bootstrap capacitor 15 under the PWM control of the low-voltage side switching transistor 14; the detection circuit 402 performs fault detection after the high-voltage bus is connected. If there is no fault, the charging is completed and the monitoring and starting stage of the load motor 5 is entered; the whole process ensures the safe start and reliable operation of the electric compressor controller and avoids drive failure caused by insufficient bootstrap capacitor voltage or circuit failure.

[0089] In this embodiment, the system also includes a device that applies the bootstrap charging circuit. This device consists of an electric compressor controller tester 16, a snap-fit ​​assembly 7, a monitoring assembly 9, and a moving module 8. The output end of the load motor 5 is connected to the input end of the electric compressor controller tester 16 via the snap-fit ​​assembly 7, transmitting the rotational power of the load motor 5 to the electric compressor controller tester 16 to drive it in compression operation. The monitoring assembly 9 is mounted on the snap-fit ​​assembly 7 and configured to monitor the current speed of the load motor 5 in real time, providing feedback signals for system control and fault diagnosis. The moving module 8 is mounted on the snap-fit ​​assembly 7 and configured to drive the snap-fit ​​assembly 7 to switch between connected and disconnected states, thereby enabling the connection or disconnection of the power transmission between the load motor 5 and the electric compressor controller tester 16. This ensures that the load motor 5 can drive the electric compressor controller tester 16 when needed, or disconnect the transmission to stop driving during maintenance, fault, or energy-saving modes. The internal structure of the electric compressor controller test machine 16 is the same as that of the existing compressor. The purpose is to simulate the actual working conditions of the load motor 5. At the same time, the load motor 5 and the related snap-fit ​​component 7, monitoring component 9 and moving module 8 in this application can also be used in the compressors of the prior art.

[0090] The snap-fit ​​assembly 7 includes a first connecting shaft 701, a claw 702, a slot 703, a base 704, a connecting rod 705, a second connecting shaft 706, and a first protrusion 707. One end of the first connecting shaft 701 is fixedly connected to the input end of the electric compressor controller tester 16 to receive power input. The claw 702 is fixedly connected to the other end of the first connecting shaft 701. The claw 702 is designed as an insertable claw shape to achieve quick snap-fit. The base 704 has a slot 703 that matches the shape of the claw 702 to accommodate and lock the clip in the connected state. Claw 702; The base 704 and the connecting rod 705 are slidably connected along the axial direction, allowing the connecting rod 705 to make limited displacement relative to the base 704; The first protrusion 707 is fixedly connected to the outer periphery of the second connecting shaft 706. The second connecting shaft 706 and the first protrusion 707 are slidably connected to the connecting rod 705 along the axial direction to realize position adjustment and force transmission. At the same time, the first protrusion 707 is set so as not to affect the joint rotation of the connecting rod 705 and the second connecting shaft 706; One end of the second connecting shaft 706 is fixedly connected to the output end of the load motor 5 for outputting the rotational power of the load motor 5.

[0091] The monitoring component 9 includes a first gear ring 901, a first gear 902, and an encoder 903. The first gear ring 901 is coaxially fixedly connected to the outer periphery of the base 704 and rotates synchronously with the base 704. The first gear ring 901 meshes with the first gear 902 to transmit the rotational motion of the base 704 to the first gear 902. The output shaft of the first gear 902 is connected to the input end of the encoder 903. The encoder 903 is configured to detect the rotational pulses or angle changes of the first gear 902, thereby calculating and outputting the real-time speed signal of the load motor 5. This signal can be transmitted to the control unit 4 to achieve closed-loop control.

[0092] The snap-fit ​​assembly 7 also includes a second protrusion 708 and a spring 709. The second protrusion 708 is fixedly connected to the outer periphery of the connecting rod 705 and is axially slidably connected to the inner wall of the seat 704, which is used to guide the movement trajectory of the connecting rod 705 and limit radial offset. The spring 709 is coaxially sleeved on the connecting rod 705. The two ends of the spring 709 are fixedly connected to the protrusion on the connecting rod 705 and the end face of the seat 704, respectively. The spring 709 is configured to provide elastic restoring force, which pushes the seat 704 to separate from the pawl 702 when the snap-fit ​​assembly 7 is disconnected, and maintains a stable elastic force when connected to ensure that the pawl 702 and the slot 703 can be properly snapped together, thereby enhancing transmission reliability and shock absorption effect.

[0093] In actual use, the system first uses the control unit 4 to control the moving module 8 to drive the snap-fit ​​assembly 7 into the connection state according to the operating requirements: the moving module 8 pushes the connecting rod 705 to move axially, so that the slot 703 on the seat 704 aligns with the claw 702 and is inserted and locked. At the same time, the purpose of the spring 709 is to provide cushioning when the slot 703 and the claw 702 are not inserted. When the slot 703 and the claw 702 are docked, the elastic force of the spring 709 is used to achieve auxiliary docking. After the connection is completed, the load motor 5 starts to rotate, and its output end transmits power to the electric compressor controller test machine 16 through the second connecting shaft 706, the connecting rod 705, the seat 704, and the first connecting shaft 701 to realize the compression operation.

[0094] Before the control docking of the mobile module 8, the monitoring component 9 performs monitoring work. The monitoring component 9 monitors the speed in real time. If the speed is abnormal (e.g., exceeding the preset upper limit or falling below the lower limit), the control unit 4 adjusts the PWM signal or interrupts the operation to protect the system. When disconnection is required, the mobile module 8 reverses the drive of the connecting rod 705, causing the slot 703 to disengage from the claw 702, thereby stopping the drive of the electric compressor controller test machine 16 and ensuring the safety and flexibility of the system during startup, operation and maintenance.

[0095] In this embodiment, the moving module 8 includes a second gear ring 801, a second gear 802, a frame 803, a reciprocating screw 804, a sliding member 805, a limiting rod 806, a connecting member 807, an outer ring 808, a pawl 809, a ratchet 810, a shaft 811, and a torsion spring 812; wherein, the second gear ring 801 is coaxially fixedly connected to the outer circumference of the outer ring 808 and rotates synchronously with the outer ring 808; the outer ring 808 is rotatably connected to the shaft 811 through a bearing or a rotating bushing, allowing the outer ring 808 to rotate relative to the shaft. Shaft 811 rotates freely; one end of shaft 811 is fixedly connected to pawl 809, the pawl of pawl 809 engages with the external teeth of ratchet 810, forming a one-way ratchet mechanism, used to allow unidirectional transmission and prevent reverse rotation; ratchet 810 is coaxially fixedly connected to the second connecting shaft 706 and rotates synchronously with the second connecting shaft 706; torsion spring 812 is coaxially sleeved on shaft 811, the two ends of torsion spring 812 are fixedly connected to the fixed point of shaft 811 and the inner wall of outer ring 808 respectively, and torsion spring 812 is configured to provide torsional restoring force. When the pawl 809 disengages from the ratchet 810, the drive shaft 811 resets; the second gear ring 801 meshes with the second gear 802 to transmit rotary motion to the second gear 802; the output shaft of the second gear 802 is fixedly connected to one end of the reciprocating screw 804, and the other end of the reciprocating screw 804 is rotatably connected to the frame 803 via a bearing; the reciprocating screw 804 is configured to convert rotary motion into linear reciprocating motion; one end of the limit rod 806 is fixedly connected to the frame 803, and the rod body of the limit rod 806 is connected to the slide... The guide hole of the moving part 805 is slidably connected to guide the sliding part 805 to move along a straight path and prevent it from deviating; the sliding part 805 is threadedly connected to the reciprocating screw 804 through an internal thread, so as to slide axially as the reciprocating screw 804 rotates; one end of the connecting part 807 is rotatably connected to the connecting rod 705 through a hinge or a rotating pin, and the other end of the connecting part 807 is fixedly connected to the sliding part 805, so as to transmit the linear motion of the sliding part 805 to the connecting rod 705, thereby driving the connection or disconnection of the snap-fit ​​assembly 7.

[0096] The first protrusion 707 and the second protrusion 708 are configured to provide limiting and transmission functions when the connecting rod 705 moves relative to the seat 704 and the second connecting shaft 706, ensuring the continuity and stability of the power transmission path. Specifically, the first protrusion 707 and the second protrusion 708 allow limited axial displacement through sliding engagement with corresponding channels or guide rails, while maintaining the synchronization of the rotary transmission. The elastic configuration of the spring 709 is to drive the axial movement of the seat 704 to compensate for gaps and alignment errors during the connection process, thereby ensuring the smooth insertion and locking of the pawl 702 and the slot 703, as well as the precise meshing of the first gear 902 and the first gear ring 901, avoiding jamming or tooth disengagement.

[0097] The functions of the movable module 8 further include: when the slider 805 moves along the reciprocating screw 804 to the side furthest from the second gear 802, the first gear 902 and the first gear ring 901 are in a misaligned state (i.e., not meshed), and the pawl 702 and the slot 703 are in a locked state, realizing the power transmission connection between the load motor 5 and the electric compressor controller test machine 16; when the slider 805 moves along the reciprocating screw 804 to the side closest to the second gear 802, the first gear 902 and the first gear ring 901 are in a meshed state for speed monitoring, and the pawl 702 and the slot 703 are in a disengaged state, realizing the power transmission disconnection between the load motor 5 and the electric compressor controller test machine 16.

[0098] It is worth noting that the load motor 5 is a servo motor, capable of reversing direction as needed. Furthermore, the direction in which the load motor 5 drives the electric compressor controller test machine 16 is opposite to the direction in which the ratchet 810 drives the pawl 809 to rotate. In other words, when the second connecting shaft 706 rotates in a specified direction, it can drive the pawl 809 to move via the ratchet 810, thereby indirectly driving the reciprocating screw 804 to rotate. This, in turn, drives the slot 703 to move towards the pawl 702 via the sliding member 805 and the connecting member 807. During the movement of the slot 703 towards the pawl 702, the load motor 5 operates at low speed. In the high-speed drive, after a period of motion, when the sliding member 805 moves to the side furthest from the second gear 802, the pawl 702 engages with the slot 703. At this time, the load motor 5 reverses, which drives the electric compressor controller test machine 16 to work. However, the reciprocating screw 804 cannot continue to transmit power due to the relationship between the ratchet 810 and the pawl 809. This invention relies on the forward and reverse rotation of the load motor 5 to achieve the normal operation of the electric compressor controller test machine 16 and the engagement of the slot 703 and the pawl 702, reducing the use of electric components and saving on usage and subsequent maintenance costs.

[0099] When it is necessary to separate the pawl 702 and the slot 703 again, since the reciprocating screw 804 at this time enables the sliding member 805 to reciprocate on the limit rod 806, continuing to control the load motor 5 to rotate forward will cause the sliding member 805 on the reciprocating screw 804 to move towards the direction of the second gear 802.

[0100] Since there is a certain redundant distance between the pawl 702 and the slot 703 and the first gear 901 and the first gear 902 when they are engaged, the sliding member 805 completes the engagement of the pawl 702 and the slot 703 or the engagement of the first gear 901 and the first gear 902 before it moves to the opposite ends during the movement of the sliding member 805.

[0101] In actual use, the system activates the moving module 8 through the control unit 4 according to the running command. The activation of the moving module 8 relies on the load motor 5 driving the ratchet 810 to drive the pawl 809 to rotate. At this time, the second gear ring 801 rotates, thereby engaging the second gear 802 to rotate, driving the reciprocating screw 804 to rotate, causing the sliding member 805 to move linearly away from the second gear 802 along the limit rod 806. The connecting member 807 pushes the connecting rod 705 to move axially. When the seat 704 and the pawl 702 are not engaged, the spring 709 is compressed. When the slot 703 on the seat 704 corresponds to the pawl 702, the elastic deformation of the spring 709 can drive the pawl 702 and the slot 703 to engage. Similarly, the meshing principle of the first gear 902 and the first gear ring 901 is the same.

[0102] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A bootstrap capacitor charging system for an electric compressor controller, characterized in that, The system includes a low-voltage power supply (1), a drive unit (2), a load motor (5), three single-phase half-bridge units (3) and a control unit (4), wherein the drive unit (2) includes a bootstrap charging circuit and the control unit (4) includes a detection circuit (402) and a control circuit (403); the low-voltage power supply positive terminal (101) of the low-voltage power supply (1) is connected to the input of the bootstrap charging circuit to provide positive charge for charging the bootstrap capacitor (15); The bootstrap charging circuit includes a reverse-current protection diode (6), a charging resistor (10), and a bootstrap capacitor (15); each of the single-phase half-bridge units (3) includes a high-voltage side switch (13) and a low-voltage side switch (14), wherein the low-voltage power supply positive terminal (101) of the low-voltage power supply (1) is connected to the bootstrap capacitor (15) through the reverse-current protection diode (6) and the charging resistor (10), and the bootstrap capacitor (15) is used to provide a gate drive voltage for the high-voltage side switch (13); the negative terminal of the bootstrap charging circuit is connected to the low-voltage side switch (14) in the three single-phase half-bridge units (3) to control the charging rate of the bootstrap capacitor (15); The electric compressor controller bootstrap capacitor charging system performs the following steps: S1: Calculate the time required to fully charge the bootstrap capacitor (15) based on the resistance and capacitance values ​​of the bootstrap charging circuit. S2: Based on the drive control frequency of the control unit (4), set the minimum duty cycle and calculate the single switching charging time of the bootstrap capacitor (15); S3: Calculate the operating time of the low-voltage side switch tube (14) in the three single-phase half-bridge units (3); S4: Control the bootstrap capacitor (15) of the corresponding single-phase half-bridge unit (3) to charge to the required voltage value; In step S1, the time required to fully charge the bootstrap capacitor is 5 times the product of the resistance value and the capacitance value. In step S2, the duration of a single switching charge is equal to the minimum duty cycle divided by the drive control frequency. In step S3, the number of pulses of the low-voltage side switch tube (14) in the single-phase half-bridge unit (3) is calculated based on the ratio of the time required to fully charge the bootstrap capacitor to the duration of a single switch charging. The required working time is obtained by dividing the number of pulses by the minimum duty cycle, and twice the value of the required working time is taken as the final working time of the low-voltage side switch tube (14) in the single-phase half-bridge unit (3). In step S4, the low-voltage side switch tube (14) in the corresponding single-phase half-bridge unit (3) is controlled to turn on for two-thirds of the working time according to the minimum duty cycle, and the bootstrap capacitor (15) in the corresponding single-phase half-bridge unit (3) is charged to the required voltage value through three turns of conduction.

2. The electric compressor controller bootstrap capacitor charging system according to claim 1, characterized in that, It also includes a fault detection step: after collecting the three-phase line voltage UVDC, the bootstrap capacitor (15) is charged; Compare the voltage UVDC with the bus voltage sampling value. If the difference between the two is less than 5%, it is determined that there is a short circuit fault in the high voltage side circuit of the half-bridge unit or the line voltage exceeds the range. If the voltage UVDC is less than the minimum preset value, it is determined that a short circuit fault has occurred in the low-voltage side circuit of the half-bridge unit. Based on the judgment result, the bootstrap capacitor (15) charging program is interrupted and a fault signal is issued.

3. The electric compressor controller bootstrap capacitor charging system according to claim 2, characterized in that, The fault detection step is implemented by a detection circuit (402), which includes a voltage divider resistor (12) and an operational amplifier chip (11). The voltage divider resistor (12) is used to sample the phase line voltage; The operational amplifier chip (11) is used to amplify the sampling voltage; It also includes the steps of monitoring the load motor (5) and starting it: after the bootstrap capacitor (15) is charged, a small PWM pulse is applied to monitor the shaft mobility response of the load motor (5). If the response exceeds the threshold, an electromechanical connection command is sent and a confirmation signal is sent. After confirmation, the high-voltage bus is closed, and the duty cycle is gradually increased to monitor the changes in shaft speed, phase current and bus voltage. If there is no abnormality, it enters normal operation; otherwise, it is interrupted and an abnormal signal is issued.

4. The electric compressor controller bootstrap capacitor charging system according to claim 1, characterized in that, The detection circuit (402) is connected to the low-voltage side switch (14) and is used to collect voltage jumps after the low-voltage side switch (14) is controlled by PWM square wave, and to determine the bridge arm shoot-through risk by the maximum voltage value and its frequency. The detection circuit (402) is capable of receiving fault detection input signals (401).

5. The electric compressor controller bootstrap capacitor charging system according to claim 1, characterized in that, The charging resistor (10) is used to limit the charging current to avoid current spikes, while optimizing the value of the charging resistor (10) so as not to limit the minimum duty cycle of the motor control algorithm.

6. The electric compressor controller bootstrap capacitor charging system according to claim 1, characterized in that, The drive unit (2) includes a driver (204) and a high-voltage side switch control signal positive terminal (201), a high-voltage side switch control signal negative terminal (202) and a low-voltage side switch control signal positive terminal (203) disposed on the driver (204). The positive terminal (201) and negative terminal (202) of the high-voltage side switch control signal are connected to the high-voltage side switch (13).

7. The electric compressor controller bootstrap capacitor charging system according to claim 1, characterized in that, The detection circuit (402) is also used to collect the three-phase line voltage UVDC after the high voltage is applied, and to determine the high voltage side or low voltage side short circuit fault based on the comparison between the voltage UVDC and the bus voltage sampling value and the comparison with the lowest preset value.

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