Insulated inverter system and method for dynamic load condition optimization

Abstract

The invention discloses an insulated inverter system and method for dynamic load condition optimization. The insulated inverter system comprises an insulated DC-DC converter and a DC-AC inverter. The insulated DC-DC converter comprises a PWM control chip, a switch element, a high-frequency transformer and an optical coupler. The output of the high-frequency transformer is rectified and filtered to generate direct-current voltage; a feedback signal extracted from the DC voltage is applied to the PWM integrated circuit chip through the optical coupler to form a feedback path, and a smoothing circuit used for filtering DC voltage impurities is added to a light emitting part or a light receiving part of an optical coupler driving circuit in the feedback path so as to optimize a transmission path of the PWM control feedback signal. According to the system and the method, the stability and the reliability of the system are remarkably improved, meanwhile, the electric shock risk is reduced, and an effective solution is provided for productization of the inverter system and development of market requirements.

Description

Technical Field

[0001] The present invention relates to an inverter system, and in particular to an insulation-type inverter system and method for optimizing dynamic load conditions. Background Art

[0002] Inverter systems are key components for power conversion and are widely used in motor-driven factory equipment, home appliances, electric vehicles, and wind power generation. They regulate voltage and frequency to achieve smooth acceleration and deceleration of the motor, thereby improving power efficiency and optimizing load control. According to statistics, over 60% of electricity consumption is used to drive motors in industrial, office, and residential electrical equipment, and inverter systems play a vital role in this process.

[0003] like Figure 1 The power supply system for driving a conventional electric motor is shown, in which an inverter system 100 is provided between an input power source and a load 200. The system consists of two parts: a converter 110, which converts AC power into DC power and is primarily responsible for voltage conversion. The other part is an inverter 120, which converts DC power into AC power and is primarily responsible for frequency conversion. In the inverter system, the connection state between the converter 110 and the inverter 120 is an important technical element. However, because the inverter system generates spike currents during rapid switching operations, this not only hinders the stable operation of the converter 110 but may also damage the semiconductor switching elements (e.g., short circuit or open circuit), leading to system operation errors and frequent failures.

[0004] The rapid development of electric vehicles, home appliances, factory automation, and wind power generation is placing increasing demands on the output quality, performance, and reliability of inverter systems. Therefore, optimizing the connection between the converter and inverter to reduce the impact of peak currents and improve system stability and reliability has become a pressing technical challenge.

[0005] To further optimize the performance of inverter systems and address the challenges they face, current research focuses on eliminating or suppressing abnormal voltages in the converter's DC output to overcome system failures and switching component damage. For example: Some existing technologies use specially designed pulse width modulation (PWM) methods to reduce the current pressure of switching elements, thereby reducing problems such as switching noise, overheating, mechanical vibration and electromagnetic interference caused by harmonics in the pulse pattern.

[0006] Other existing technologies calculate the error between the converter input current value and the user command current value, and generate a control signal based on the error to adjust the pulse width of the PWM module, thereby eliminating the influence of the low-frequency ripple component caused by the structural characteristics of the inverter circuit.

[0007] Some existing technologies are also dedicated to preventing harmonics or ripple components caused by faults in switching elements in the converter, avoiding the accumulation of component fatigue caused by these abnormal operations, and thus extending the service life of the system.

[0008] While these existing technologies can mitigate the effects of harmonics and ripple to a certain extent, they still struggle to effectively address inverter system anomalies caused by sudden load fluctuations. These output anomalies can adversely affect the proper operation of the converter's PWM module, limiting the system's overall performance and reliability. Therefore, further optimizing the inverter system's feedback signal processing and dynamic response capabilities to enhance its stability and reliability under complex operating conditions remains a key research focus. Summary of the Invention

[0009] In order to address the deficiencies of the above technologies, the present invention provides an isolation inverter system and method for optimizing dynamic load conditions.

[0010] In order to solve the above technical problems, the technical solution adopted by the present invention is: an insulation type inverter system with optimized dynamic load conditions, comprising: Isolated DC-DC converters and DC-AC inverters; The isolated DC-DC converter includes a PWM control chip, a switching element, a high-frequency transformer, and an optical coupler; The output of the high-frequency transformer is rectified and filtered to generate a DC voltage; The feedback signal extracted from the DC voltage is applied to the PWM integrated circuit chip through an optocoupler to form a feedback path. In the feedback path, the light-emitting part or light-receiving part of the optocoupler driving circuit is attached with a smoothing circuit for filtering out DC voltage impurities to optimize the transmission path of the PWM control feedback signal.

[0011] Furthermore, a smoothing circuit is added to the light emitting circuit of the optical coupler to purify the feedback signal before transmission.

[0012] Furthermore, a smoothing circuit is added to the light receiving circuit of the optical coupler to perform secondary purification on the feedback signal after optical isolation transmission.

[0013] Furthermore, the smoothing circuit includes a diode D1, a resistor R1 and a capacitor C1; The anode of the diode D1 is connected to the DC voltage output terminal of the high-frequency transformer; The cathode of diode D1 is connected to one end of resistor R1; The other end of resistor R1 is connected to the positive terminal of capacitor C1; The negative electrode of capacitor C1 is grounded; The cathode of the diode D2 is connected to the DC voltage output terminal of the high-frequency transformer; The anode of diode D2 is connected to the positive terminal of capacitor C2; The negative electrode of capacitor C2 is grounded; One end of the resistor R2 is connected to the common end of the diode D2 and the capacitor C2; The other end of the resistor R2 is connected to a common end of the diode D1 and the capacitor C1.

[0014] Furthermore, the output end of the PWM control chip is connected to the control end of the switching element, which is used to control the conduction and cutoff of the switching element; the input end of the switching element is connected to the DC power supply, and its output end is connected to the primary winding of the high-frequency transformer to convert the DC voltage into a high-frequency pulse voltage and apply it to the high-frequency transformer.

[0015] Furthermore, the secondary winding output end of the high-frequency transformer is connected to a rectifier and filter circuit to convert the high-frequency AC voltage into a stable DC voltage.

[0016] Furthermore, the output end of the rectifier and filter circuit is connected to a grounded capacitor to output a DC voltage.

[0017] Furthermore, the switching element is a metal oxide semiconductor field effect transistor or an insulated gate bipolar transistor.

[0018] An optimization method for an isolated inverter system with dynamic load condition optimization, the optimization method comprising the following steps: S1. Extracting feedback signal: sampling the original feedback signal by dividing the DC voltage output by the isolated DC-DC converter; S2, signal purification processing: The original feedback signal is input into the smoothing circuit. Through the synergistic effect of diode buffering, resistor voltage division and capacitor filtering, high-frequency noise and pulse interference caused by sudden load changes are eliminated to generate a pure DC component signal; S3, isolated transmission: The purified DC component signal is electrically isolated through the optical coupler and transmitted to the PWM control chip; S4. Dynamic adjustment control: Based on the pure DC component signal, the PWM control chip adjusts the duty cycle of the switching element in real time to stabilize the DC voltage within the set voltage range.

[0019] Furthermore, the PWM control chip dynamically adjusts the duty cycle through the feedback signal purified by the smoothing circuit, so that the DC voltage is stabilized within the range of 310V to 600V.

[0020] The present invention discloses an isolated inverter system and method for optimizing dynamic load conditions. By introducing a smoothing circuit into the feedback path of an isolated DC-DC converter, the present invention effectively solves the system abnormalities mentioned in the background art caused by sudden load changes, such as vibration, noise, damage to switching elements, and the risk of electric shock. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a diagram of the power supply system used to drive an ordinary electric motor.

[0022] Figure 2 The inverter system block diagram of an isolated DC-DC converter circuit without a smoothing circuit is shown.

[0023] Figure 3 This is a block diagram of the inverter system of the present invention.

[0024] Figure 4 It is a basic structural diagram of the smoothing circuit in the present invention.

[0025] In the figure: 100, inverter system; 200, load; 110, isolated DC-DC converter; 111, PWM control chip; 112, switching element; 113, high-frequency transformer; 114, grounding capacitor; 115, optocoupler; 116, smoothing circuit; 120, DC-AC inverter. DETAILED DESCRIPTION

[0026] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0027] An isolated inverter system optimized for dynamic load conditions aims to improve system stability and reliability while reducing the risk of electric shock by optimizing the transmission path of feedback signals. By introducing a smoothing circuit into the isolated DC-DC converter, the system purifies the feedback signal, ensuring efficient operation under dynamic load conditions.

[0028] like Figure 2The device shown specifically includes an isolated DC-DC converter 110, which includes a PWM control chip 111, a switching element 112, a high-frequency transformer 113, and an optocoupler 115. The output of the high-frequency transformer 113 is rectified and filtered to generate a DC voltage. The output of the PWM control chip 111 is connected to the control terminal of the switching element 112, which is used to control the conduction and cutoff of the switching element 112. The switching element 112 can be a metal oxide semiconductor field effect transistor or an insulated gate bipolar transistor. The input of the switching element 112 is connected to a DC power source, and its output is connected to the primary winding of the high-frequency transformer 113 to convert the DC voltage into a high-frequency pulse voltage and apply it to the high-frequency transformer 113. The output of the secondary winding of the high-frequency transformer 113 is connected to a rectifier and filter circuit to convert the high-frequency AC voltage into a stable DC voltage. The output of the rectifier and filter circuit is connected to a grounded capacitor 114 to output a DC voltage. The DC-AC inverter 120 converts the DC voltage into an AC voltage for driving a load.

[0029] The feedback signal extracted from the DC voltage is applied to the PWM integrated circuit chip 111 via an optocoupler 115, forming a feedback path. Previously, the DC-DC converter's function was to rectify the AC input power to DC power on the primary side, then perform power factor correction (PFC) on this primary DC output before applying it to the switching component. The pulse voltage generated by the switching component is then buck-boosted and outputted via a high-frequency transformer. This buck-boost voltage is then rectified twice to output a DC voltage. The DC output voltage Vout at this point is smoothed to a certain degree by the capacitor before being applied to the inverter's drive circuit. The DC-DC converter uses a feedback signal to maintain the DC output voltage Vout at the set target value. This feedback signal is then transmitted to the PWM integrated circuit chip, supporting duty cycle adjustment. In this case, the DC-DC converter's DC output voltage (Vout) is designed to vary between 310 and 600V using duty cycle control to drive the inverter system's rated output of 220V. While inverter systems connected to isolated DC-DC converters present no particular issues under no-load conditions, the sudden change in load speed causes pulse current fluctuations, which can damage the isolated DC-DC converter's switching elements and generate abnormalities such as vibration and noise. This issue remains unresolved. Using a conventional transformer to boost the converter's output voltage (Vout) consumes power even under no-load conditions and, due to noise and excessive weight, does not meet user needs. Consequently, the commercialization of inverter systems that utilize isolated DC-DC converters to achieve safe operation and the development of market demand remain insufficient.

[0030] like Figure 3As shown, the present invention has developed an inverter system that reduces the risk of electric shock while maintaining stable performance. Specifically, a smoothing circuit 116 is added to the light-emitting or light-receiving portion of the optocoupler 115 drive circuit in the feedback path to filter out DC voltage impurities, thereby optimizing the transmission path of the PWM control feedback signal. Experiments revealed the root cause of the problem in the feedback circuit of the isolated DC-DC converter. It was confirmed that simply improving the feedback circuit alone could achieve an inverter system without switching element damage, vibration, or noise, leading to the present invention. Specifically, if Figure 4 The smoothing circuit 116 shown includes a diode D1, a resistor R1, and a capacitor C1. The anode of diode D1 is connected to the DC voltage output terminal of the high-frequency transformer 113. The cathode of diode D1 is connected to one end of resistor R1. The other end of resistor R1 is connected to the positive terminal of capacitor C1. The negative terminal of capacitor C1 is grounded. The cathode of diode D2 is connected to the DC voltage output terminal of the high-frequency transformer 113. The anode of diode D2 is connected to the positive terminal of capacitor C2. The negative terminal of capacitor C2 is grounded. One end of resistor R2 is connected to the common terminal of diode D2 and capacitor C2. The other end of resistor R2 is connected to the common terminal of diode D1 and capacitor C1. By introducing the smoothing circuit 116, the feedback signal is purified to ensure its purity and stability. Diode D1 conducts forward to delay the transfer of Vout sudden energy. Diode D2 is connected in reverse parallel to provide overvoltage protection. Resistors R1 and R2 divide the voltage and provide appropriate damping to reduce high-frequency noise. Capacitors C1 and C2 act as filters to remove high-frequency components and ensure that the feedback signal is a pure DC component. This is an insulation inverter system optimized for dynamic inductive load conditions that eliminates abnormalities such as vibration and noise even under rapidly changing load conditions, reducing damage or failure of switching components while also eliminating the risk of electric shock in the power system applied to the load.

[0031] like Figure 4As shown, while conventionally, the feedback signal is extracted directly from the converter's output terminal Vout, the present invention utilizes a smoothing circuit to extract it. In a preferred embodiment of the present invention, the smoothing circuit consists of two diodes, two resistors, and two capacitors. This circuit structure removes the pulse voltage and high-frequency components contained in the converter's output, allowing the filtered feedback signal to be applied to the optocoupler. The diodes act as buffers, allowing the fluctuating output voltage to slowly charge into the capacitors. The output voltage is also divided to extract the appropriate feedback signal. The capacitors are configured to bypass the high-frequency components in the output voltage, and the purified feedback signal is applied to the PWM control chip via a flat DC component, thereby controlling the output voltage to not fall below the designed lower limit. For example, when the inverter system's rated output is designed for 220V, it is necessary to maintain the output voltage within a range of 600V from a lower limit of 310V. The feedback signal extracted by the smoothing circuit is controlled to keep the output voltage above the lower limit of 310V. By adding a smoothing circuit to the feedback loop of an isolated DC-DC converter, the filtered DC component feedback signal enables safe control of the PWM control chip. This reduces damage to switching elements and malfunctions even under drastic load changes. Repeated experiments have confirmed that abnormalities such as noise and vibration are significantly reduced.

[0032] In some embodiments, a smoothing circuit 116 is added to the light-emitting circuit of the optical coupler 115 to clean the feedback signal before transmission.

[0033] In other embodiments, smoothing circuit 116 is added to the light-receiving circuit of optocoupler 115 to perform secondary purification on the feedback signal after optical isolation and transmission. Even though this embodiment incurs an increase in manufacturing cost, adding smoothing circuits to both the light-emitting and light-receiving parts of the optocoupler can provide a more stable and pure DC component feedback signal to the PWM control chip.

[0034] The most significant feature is the selective addition of a smoothing circuit to the PWM control feedback circuit. This means that a smoothing circuit can be added to either or both sides of the optocoupler's light-emitting or light-receiving circuits.

[0035] At the same time, the present invention discloses an optimization method for an insulation type inverter system with dynamic load condition optimization, the optimization method comprising the following steps: S1. Extracting feedback signal: sampling the original feedback signal by dividing the DC voltage output by the isolated DC-DC converter 110; S2. Signal purification: The original feedback signal is input into the smoothing circuit 116. Through the synergistic effect of diode buffering, resistor voltage division and capacitor filtering, high-frequency noise and pulse interference caused by sudden load changes are eliminated to generate a pure DC component signal. S3, isolated transmission: the purified DC component signal is electrically isolated via the optical coupler 115 and transmitted to the PWM control chip 111; S4. Dynamic adjustment control: Based on the pure DC component signal, the duty cycle of the switch element 112 is adjusted in real time through the PWM control chip 111 to stabilize the DC voltage within the set voltage range.

[0036] Therefore, the PWM control chip 111 dynamically adjusts the duty cycle through the feedback signal purified by the smoothing circuit 116, so that the DC voltage is stabilized within the range of 310V to 600V. The present invention effectively solves the system abnormalities caused by sudden load changes mentioned in the background technology, such as vibration, noise, damage to switching elements, and the risk of electric shock, by introducing a smoothing circuit in the feedback path of the isolated DC-DC converter. Specifically, the smoothing circuit purifies the feedback signal, removes high-frequency noise and pulse interference, and ensures the purity and stability of the feedback signal. This enables the PWM control chip to dynamically adjust the duty cycle according to the accurate feedback signal, thereby stabilizing the output voltage, reducing damage to the switching elements, and reducing the risk of electric shock. In addition, by adding a smoothing circuit to the light-emitting part or light-receiving part circuit of the optocoupler, the present invention further improves the stability and reliability of the system. In summary, the present invention provides an isolated inverter system optimized under dynamic load conditions, significantly improving the stability and reliability of the system, while reducing the risk of electric shock, and providing an effective solution for the productization of the inverter system and the development of market demand.

[0037] The above embodiments are not limitations of the present invention, and the present invention is not limited to the above examples. Any changes, modifications, additions or substitutions made by technicians in this technical field within the scope of the technical solution of the present invention also fall within the scope of protection of the present invention.

Claims

1. An insulation type inverter system optimized for dynamic load conditions, characterized in that: include: an isolated DC-DC converter (110) and a DC-AC inverter (120); The isolated DC-DC converter (110) comprises a PWM control chip (111), a switching element (112), a high-frequency transformer (113) and an optical coupler (115); the output of the high-frequency transformer (113) is rectified and filtered to generate a DC voltage; a feedback signal extracted from the DC voltage is applied to the PWM integrated circuit chip (111) via the optical coupler (115) to form a feedback path; in the feedback path, a light-emitting part or a light-receiving part of the optical coupler (115) driving circuit is additionally provided with a smoothing circuit (116) for filtering out DC voltage impurities to optimize the transmission path of the PWM control feedback signal.

2. The dynamic load condition optimized isolation inverter system according to claim 1, characterized in that: The smoothing circuit (116) is attached to the light-emitting circuit of the optical coupler (115) to purify the signal before the feedback signal is transmitted.

3. The dynamic load condition optimized isolation inverter system according to claim 2, characterized in that: The smoothing circuit (116) is attached to the light receiving circuit of the optical coupler (115) to perform secondary purification on the feedback signal after optical isolation transmission.

4. The dynamic load condition optimized insulation inverter system according to claim 2 or 3, characterized in that: The smoothing circuit (116) includes a diode D1, a resistor R1 and a capacitor C1; The anode of the diode D1 is connected to the DC voltage output terminal of the high-frequency transformer (113); The cathode of diode D1 is connected to one end of resistor R1; The other end of resistor R1 is connected to the positive terminal of capacitor C1; The negative electrode of capacitor C1 is grounded; The cathode of the diode D2 is connected to the DC voltage output terminal of the high-frequency transformer (113); The anode of diode D2 is connected to the positive terminal of capacitor C2; The negative electrode of capacitor C2 is grounded; One end of the resistor R2 is connected to the common end of the diode D2 and the capacitor C2; The other end of the resistor R2 is connected to a common end of the diode D1 and the capacitor C1.

5. The dynamic load condition optimized isolation inverter system according to claim 4, characterized in that: The output end of the PWM control chip (111) is connected to the control end of the switch element (112) for controlling the on and off of the switch element (112); the input end of the switch element (112) is connected to a DC power supply, and the output end is connected to the primary winding of a high-frequency transformer (113) to convert the DC voltage into a high-frequency pulse voltage and apply it to the high-frequency transformer (113).

6. The dynamic load condition optimized isolation inverter system according to claim 1, characterized in that: The secondary winding output end of the high-frequency transformer (113) is connected to a rectifier and filter circuit to convert the high-frequency AC voltage into a stable DC voltage.

7. The dynamic load condition optimized isolation inverter system according to claim 1, characterized in that: The output end of the rectifier and filter circuit is connected to a grounding capacitor (114) and outputs a DC voltage.

8. The dynamic load condition optimized isolation inverter system according to claim 1, characterized in that: The switching element (112) is a metal oxide semiconductor field effect transistor or an insulated gate bipolar transistor.

9. A method for optimizing an isolated inverter system under dynamic load conditions, characterized in that: The optimization method comprises the following steps: S1. Extracting feedback signals: sampling the original feedback signal by voltage division from the DC voltage output by the isolated DC-DC converter (110); S2. Signal purification processing: inputting the original feedback signal into the smoothing circuit (116), eliminating high-frequency noise and pulse interference caused by load mutation through the synergistic effect of diode buffering, resistor voltage division and capacitor filtering, and generating a pure DC component signal; S3. Isolation transmission: electrically isolating the purified DC component signal through the optical coupler (115) and transmitting it to the PWM control chip (111); S4. Dynamic adjustment control: adjusting the duty cycle of the switching element (112) in real time based on the pure DC component signal through the PWM control chip (111), so that the DC voltage is stabilized within a set voltage range.

10. The optimization method for an isolated inverter system with dynamic load condition optimization according to claim 9, characterized in that: The PWM control chip (111) dynamically adjusts the duty cycle through the feedback signal purified by the smoothing circuit (116), so that the DC voltage is stabilized within the range of 310V to 600V.

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