An active interactive boost PFC frequency converter for three-phase 400V power grid

Abstract

The utility model discloses a kind of active interactive boost PFC frequency converter for three-phase 400V power grid, including box and inside sequentially connected multistage three-phase input EMI filter unit, three-phase rectifier unit, active boost PFC unit, DC bus capacitor group and three-phase inverter unit.Wherein, the active boost PFC unit includes boost inductance and IGBT, by control unit drive, rectification, boost and correct power factor to a stable DC bus voltage of wide-range fluctuation input voltage;Meanwhile, the multistage EMI filter unit is suppressed high-frequency interference by at least two levels of filter inductance.The utility model makes that frequency converter can stably output 35kW rated power in the wide input voltage range of 380V~480V, solves the problem that traditional frequency converter cannot full load and power factor is low under low voltage, significantly improves the overall efficiency, power grid adaptability and power quality.

Description

Technical Field

[0001] This utility model relates to the field of power electronics technology, and in particular to a three-phase 400V high-power active interactive boost PFC frequency converter suitable for industrial power grids. Background Technology

[0002] In the industrial and energy sectors, high-power three-phase 400V frequency converters are core devices driving equipment such as compressors, pumps, and fans. Currently, most frequency converters at this power level still use the traditional, low-cost passive power factor correction (PFC) scheme. This scheme has two inherent drawbacks: First, its DC bus voltage is entirely dependent on the instantaneous value of the input AC grid voltage. When the grid voltage is at the lower limit of the allowable range (e.g., 380V), the DC bus voltage drops accordingly, causing the downstream inverter circuit to be unable to generate sufficient voltage to drive the motor to achieve rated torque and power, resulting in the frequency converter not operating at full load and the equipment not performing to its full potential. Second, passive rectification leads to severe distortion of the input current waveform, high harmonic content, and low power factor, causing not only additional energy loss but also pollution to the public power grid, making it difficult to meet stringent industrial power quality standards such as EN 61000-3-12.

[0003] To address power issues, users are often forced to choose inverters with higher power ratings, increasing initial investment and installation space. Therefore, the industry urgently needs a high-power inverter solution that can maintain stable output power over a wide voltage range while possessing a high input power factor and low harmonic distortion. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of existing technologies and provide an active interactive boost converter (PFC) for a three-phase 400V power grid. It not only provides stable output of rated power over a wide input voltage range, but also effectively improves the input power factor and reduces harmonic interference to the power grid.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: An active interactive boost PFC frequency converter for a three-phase 400V power grid includes a housing and a main circuit disposed within the housing. The main circuit includes a multi-stage three-phase input EMI filter unit, a three-phase rectifier unit, an active boost PFC unit, a DC bus capacitor bank, a three-phase inverter unit, and a control unit.

[0006] The input terminal of the multi-stage three-phase input EMI filter unit is used to connect to a 380~480V three-phase power grid. It contains at least two stages of filter inductors to form a multi-stage filter network, which is used to strongly suppress high-frequency conducted interference from the power grid and the inverter itself.

[0007] The AC side of the three-phase rectifier unit is connected to the output terminal of the multi-stage three-phase input EMI filter unit.

[0008] The input terminal of the active boost PFC unit is connected to the DC side of the three-phase rectifier unit; the unit includes at least one boost inductor and at least one controllable power switch with an insulated gate bipolar transistor as its core, which is configured to simultaneously perform two core functions: DC voltage boost and input power factor correction.

[0009] The input terminal of the DC bus capacitor bank is connected to the output terminal of the active boost PFC unit.

[0010] The DC side of the three-phase inverter unit is connected in parallel with the DC bus capacitor bank.

[0011] The control unit is configured to sample input and output parameters, and by precisely controlling the on and off of the IGBT, it improves and stabilizes the power energy after rectifying the fluctuating input voltage to a preset DC bus voltage value, while forcing the input current waveform to be sinusoidal and in phase with the voltage, thereby achieving a high power factor.

[0012] Preferably, the active boost PFC unit adopts an interleaved parallel Boost PFC circuit topology to reduce input current ripple and improve system power density.

[0013] Preferably, the three-phase inverter unit is a three-phase full-bridge topology, and a clamping diode is connected in series between the midpoint of each bridge arm and the DC bus to effectively suppress IGBT turn-off overvoltage and improve system reliability.

[0014] Compared with existing technologies, the frequency converter provided by this invention solves the problem of traditional passive PFC frequency converters being unable to operate at full load due to insufficient bus voltage at low input voltages by introducing an active front-end topology that integrates boost and PFC functions, supplemented by multi-stage EMI filtering. This ensures a stable output of 35kW rated power across the entire voltage range of 380V to 480V, greatly improving the equipment's adaptability to fluctuating power grids. Simultaneously, this invention actively achieves a high input power factor close to 1, significantly reducing input current harmonic distortion and making the frequency converter a "grid-friendly" load, effectively reducing grid pollution. Furthermore, for medium- and high-voltage high-power applications, IGBTs are preferred as boost switching transistors, optimizing system conduction losses and improving overall energy efficiency and heat dissipation reliability in the medium- and high-power range. The multi-stage EMI filtering structure ensures stable operation of the frequency converter in harsh industrial electromagnetic environments. Attached Figure Description

[0015] Figure 1 This is the main circuit topology diagram of this utility model. Detailed Implementation

[0016] The technical solution protected by this utility model will be described in detail below with reference to the accompanying drawings.

[0017] See Figure 1 The present invention provides an active interactive boost PFC frequency converter for a three-phase 400V power grid. Its main circuit topology includes a multi-stage three-phase input EMI filter unit 10, a three-phase rectifier unit 20, an active boost PFC unit 30, a DC bus capacitor bank 40, a three-phase inverter unit 50, and a control unit (not shown).

[0018] The input terminal of the multi-stage three-phase input EMI filter unit 10 is connected to a 380~480V three-phase industrial power grid. This unit adopts a multi-stage filtering architecture. In this embodiment, the multi-stage three-phase input EMI filter unit 10 includes a first-stage differential-mode inductor (L1, L2, L3) and a second-stage differential-mode inductor (L4, L5, L6) connected in series in the three-phase lines. These, along with multiple sets of differential-mode capacitors (such as C4, C5, C6, C7, C8, C9) connected across the phase lines, together form an effective differential-mode noise suppression network.

[0019] The three-phase rectifier unit 20 is a three-phase full-bridge rectifier circuit composed of rectifier diodes (DL1, DL2, DL3, DL4, DL9, DL10). Its AC side is connected to the output terminal of the EMI filter unit 10, converting the filtered three-phase AC power into pulsating DC power.

[0020] The active boost PFC unit 30 adopts an interleaved parallel Boost PFC circuit, including a first boost branch and a second boost branch connected in parallel. The first boost branch consists of a first boost inductor L4, a first boost diode DL19, and a first controllable switch S1 (IGBT). The second boost branch consists of a second boost inductor L5, a second boost diode DL20, and a second controllable switch S2 (IGBT). Specifically, taking the first branch as an example, one end of the first boost inductor L4 is connected to the positive output terminal of the rectifier unit 20, and the other end is connected to the anode of the first boost diode DL19 and the collector of the first IGBT (S1); the cathode of the first boost diode DL19 is connected to the positive terminal of the DC bus capacitor bank 40; and the emitter of the first IGBT (S1) is connected to the negative terminal of the DC bus capacitor bank 40.

[0021] The DC bus capacitor bank 40 consists of four parallel 470μF electrolytic capacitors (CL9, CL10, CL11, CL12), connected between the positive and negative terminals of the bus, used to stabilize the DC voltage and provide energy buffer for the inverter unit.

[0022] The three-phase inverter unit 50 is a three-phase full-bridge structure, employing six IGBT modules (SWIGBT1, such as S10, S20, S30, S3, S40, S4) and their anti-parallel freewheeling diodes (DL5, DL7, DL11, DL15, DL13, DL17). To enhance reliability, clamping diodes (DL6, DL8, DL12, DL16, DL14, DL18) are connected in series between the midpoint of each bridge arm and the DC bus P or N to absorb overvoltage spikes during switching.

[0023] The control unit samples the grid input voltage, input current, and DC bus voltage in real time. In this embodiment, the control unit is a DSP, such as the Texas Instruments (TI) TMS320F2837x series dual-core DSP or the Infineon AURIX™ series TC3xx microcontroller. The control unit generates two phase-interleaved control signals (PWM) through built-in voltage outer loop and current inner loop control algorithms. These signals are then applied to the gates of the first IGBT (S1) and the second IGBT (S2) respectively after passing through the drive circuit. Simultaneously, by precisely controlling the duty cycle of the IGBTs, the rectified pulsating DC current is boosted and stabilized at a high preset DC voltage (e.g., 700-800VDC) much higher than the 480V input peak value, ensuring subsequent inverter capability. Furthermore, the current loop control ensures that the input current waveform closely tracks the sinusoidal waveform of the input voltage, achieving unity power factor correction. This allows the inverter to continuously output a rated power of 35kW and a rated current of 50A across the entire input voltage range.

[0024] The above description is merely an embodiment of this utility model and does not limit the patent scope of this utility model. Any equivalent structural or procedural transformations made based on the description and drawings of this utility model, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this utility model.

Claims

1. An active interactive boost converter (PFC) for a three-phase 400V power grid, comprising a housing and a main circuit disposed within the housing, characterized in that, The main circuit includes: A multi-stage three-phase input EMI filter unit, the input of which is used to connect to a 380~480V three-phase power grid, the multi-stage EMI filter unit includes at least two stages of filter inductors; The three-phase rectifier unit has its AC side connected to the output terminal of the multi-stage three-phase input EMI filter unit. An active boost PFC unit has its input terminal connected to the DC side of the three-phase rectifier unit; the active boost PFC unit includes at least one boost inductor and at least one controllable power switch, and the active boost PFC unit is configured to simultaneously achieve DC boost and input power factor correction; The input terminal of the DC bus capacitor bank is connected to the output terminal of the active boost PFC unit; The three-phase inverter unit has its DC side connected in parallel with the DC bus capacitor bank; The control unit is configured to control the on and off of the controllable power switch to stabilize the DC bus voltage at a preset value.

2. The active interactive boost converter (PFC) for a three-phase 400V power grid according to claim 1, characterized in that, The active boost PFC unit includes a first boost branch and a second boost branch connected in parallel. The first boost branch includes a first boost inductor, a first boost diode, and a first controllable switch. One end of the first boost inductor is connected to the DC side of the three-phase rectifier unit, and the other end is connected to the anode of the first boost diode and the anode of the first controllable switch, respectively. The cathode of the first boost diode is connected to the positive terminal of the DC bus capacitor bank. The cathode of the first controllable switch is connected to the negative terminal of the DC bus capacitor bank, and its control terminal is connected to the control unit. The second boost branch includes a second boost inductor, a second boost diode, and a second controllable switch; one end of the second boost inductor is connected to the DC side of the three-phase rectifier unit, and the other end is connected to the positive terminal of the second boost diode and the positive terminal of the second controllable switch, respectively; the negative terminal of the second boost diode is connected to the positive terminal of the DC bus capacitor bank; the negative terminal of the second controllable switch is connected to the negative terminal of the DC bus capacitor bank, and its control terminal is connected to the control unit.

3. The active interactive boost converter (PFC) for a three-phase 400V power grid according to claim 2, characterized in that, The first controllable switch and the second controllable switch are insulated gate bipolar transistors, with their collectors serving as their corresponding positive terminals, their emitters serving as their corresponding negative terminals, and their gates serving as their corresponding control terminals.

4. The active interactive boost converter (PFC) for a three-phase 400V power grid according to claim 1, characterized in that, The DC bus capacitor bank consists of four electrolytic capacitors with a capacity of 470μF connected in parallel.

5. An active interactive boost converter (PFC) for a three-phase 400V power grid according to claim 1, characterized in that, The multi-stage three-phase input EMI filter unit includes at least two stages of filter inductors, including a first stage inductor and a second stage inductor connected in series.

6. An active interactive boost converter (PFC) for a three-phase 400V power grid according to claim 1, characterized in that, The three-phase rectifier unit is a six-channel rectifier bridge.

7. An active interactive boost converter (PFC) for a three-phase 400V power grid according to claim 1, characterized in that, The three-phase inverter unit is a three-phase full-bridge structure, and a clamping diode for overvoltage clamping is connected in series between the midpoint of each bridge arm and the DC bus.

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