High-voltage power generation controller based on biphase interleaving Buck topology

Abstract

The invention discloses a high-voltage power generation controller based on a biphase interleaving Buck topology. The high-voltage power generation controller comprises a power circuit and a control system. The power circuit is formed by connecting two Buck circuits in parallel, and stable direct-current voltage is output under the wide rotating speed range of the generator. According to the control system, a DSP generates two paths of PWM signals with the phase difference of 180 degrees, the PWM signals drive switching tubes of two paths of Buck circuits respectively after passing through an MOSFET drive circuit, and the duty ratio of the PWM signals is adjusted by sampling output voltage and inductive current and adopting voltage and current double-closed-loop control, so that it is guaranteed that the output voltage of a generator controller meets the requirement. Through the interleaving technology, input and output current ripples are effectively reduced, the requirements for an input power supply and an output filter capacitor are reduced, and the system efficiency and the power density are improved.

Description

Technical Field

[0001] This invention relates to the field of power electronic converter and motor control technology, specifically to a high-voltage DC power generation system controller for platforms such as aircraft, ships, and special vehicles. Background Technology

[0002] With the development of multi-electrified and fully electrified platforms, higher requirements are placed on the power rating, power quality, and reliability of airborne power systems. 270VDC high-voltage direct current generation systems have been widely used due to their high efficiency and simple power distribution.

[0003] Because the engine has a wide speed range, the AC voltage generated by the high-voltage brushless permanent magnet generator operating coaxially with it also varies during power generation. Therefore, the DC voltage obtained after passing through a three-phase bridge rectifier circuit has a large voltage range, necessitating the use of a Buck circuit to step down the DC bus voltage. Traditional controllers often employ a single-channel Buck converter topology. However, this approach has the following inherent drawbacks: 1. Large current ripple: The input and output current ripple of a single-phase Buck circuit is large, which puts high stress on the input power supply and output filter capacitors, requiring larger capacitance values, increasing size and cost.

[0004] 2. Conflict between dynamic response and reliability: In order to improve power and dynamic response, the power level of a single Buck converter needs to be increased. However, high-power single-tube switching devices (such as MOSFETs and IGBTs) have higher switching and conduction losses, more complex heat dissipation design, and a single point of failure can cause the entire power generation system to fail, resulting in low reliability.

[0005] 3. Severe electromagnetic interference: Large current ripple can cause severe electromagnetic interference problems, affecting the normal operation of other sensitive equipment on the platform.

[0006] Therefore, there is an urgent need for a generator controller solution that can meet the requirements of high voltage and high power output, and also features low ripple and high reliability. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of the prior art and provide a high-voltage generator controller based on a two-phase interleaved parallel Buck topology, which can effectively reduce current ripple, improve system efficiency and power density, achieve redundant control, and enhance system reliability.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: A high-voltage power generation controller based on a two-phase interleaved parallel Buck topology includes a two-phase Buck parallel power circuit and a control system; The dual-phase Buck parallel power circuit has its input terminal connected to the bus voltage after three-phase bridge rectification, and its output terminal connected to the load. Under the control of the control system, the bus voltage is stepped down to achieve a stable DC voltage output by the controller under a wide speed range of the generator. The control system generates two PWM signals with a 180° phase difference to drive the switching transistors of the dual-phase Buck parallel power circuit; it samples the output voltage and inductor current of the dual-phase Buck parallel power circuit, and uses voltage and current dual closed-loop control to adjust the duty cycle of the PWM signals to ensure that the output voltage of the dual-phase Buck parallel power circuit meets the requirements.

[0009] Preferably, the dual-phase Buck parallel power circuit includes a first Buck branch, a second Buck branch, a bus support capacitor Cin, and an output filter capacitor Co; The first Buck branch includes switching transistor S1, switching transistor S2, and inductor L1; The second Buck branch includes switching transistor S3, switching transistor S4, and inductor L2; The bus support capacitor Cin is connected between the positive and negative terminals of the bus voltage; the drain of the switching transistor S1 is connected to the positive terminal of the bus voltage, and the source of the switching transistor S1 is connected to one end of the inductor L1 and the drain of the switching transistor S2; the source of the switching transistor S2 is connected to the negative terminal of the bus voltage; the other end of the inductor L1 is connected to the positive terminal of the output filter capacitor Co, and the output voltage is connected to the positive terminal of the load after being filtered by the output capacitor Co. The drain of switch S3 is connected to the positive terminal of the bus voltage, and the source of switch S3 is connected to one end of inductor L2 and the drain of switch S4. The source of switch S4 is connected to the negative terminal of the bus voltage. The other end of inductor L2 is connected to the positive terminal of output filter capacitor Co. The output voltage is filtered by output capacitor Co and then connected to the positive terminal of the load. The source terminals of switching transistors S2 and S4 are connected and used as the negative terminal of the load, while also being grounded.

[0010] Preferably, the control system generates two PWM signals with a phase difference of 180°. The first PWM signal is connected to the gates of switching transistors S1 and S2, and the second PWM signal is connected to the gates of switching transistors S3 and S4.

[0011] Preferably, the control system includes a voltage and current sampling circuit, a sampling conditioning circuit, a DSP minimum system circuit, and a MOSFET driving circuit; Voltage and current sampling circuit: used to sample the bus voltage, the output voltage of the two-phase Buck parallel power circuit, and the inductor current in the first Buck branch and the second Buck branch, and send them to the sampling and conditioning circuit; Sampling and conditioning circuit: The bus voltage, output voltage of the two-phase Buck parallel power circuit and inductor current sampled by the voltage and current sampling circuit are conditioned and the conditioned signals are transmitted to the DSP minimum system circuit for processing. DSP minimum system circuit: realizes current-voltage A / D conversion, and generates two PWM signals with dead time and 180° phase difference based on the output voltage and inductor current using voltage and current dual closed-loop control; MOSFET drive circuit: The two PWM signals are amplified. The amplified first PWM signal is used to drive the switching transistors S1 and S2 of the first Buck branch, and the amplified second PWM signal is used to drive the switching transistors S3 and S4 of the second Buck branch.

[0012] Preferably, the voltage and current sampling circuit includes a voltage sampling sub-circuit and a current sampling sub-circuit. The voltage sampling sub-circuit uses a resistor divider method to divide the bus voltage and the output voltage of the two-phase Buck parallel power circuit. Then, a set of differential signals is obtained through an isolation differential operational amplifier and sent to the sampling conditioning circuit. The current sampling sub-circuit uses a current sensor. The inductor currents in the first Buck branch and the second Buck branch are converted into voltage signals after passing through the current sensor and sent to the sampling and conditioning circuit.

[0013] Preferably, the control system further includes a fault detection and redundancy control module, used to monitor the output current of the two Buck branches in real time; when a fault is detected in a Buck branch, fault information is sent to the DSP minimum system circuit. After receiving information that a Buck branch has failed, the DSP minimum system circuit stops sending PWM signals to the failed branch and adjusts the PWM duty cycle of the other normal branch to maintain the output voltage of the two-phase Buck parallel power circuit.

[0014] The advantages of this invention compared to the prior art are: (1) By adopting an interleaved parallel topology, the two-phase Buck circuits operate at 180° intervals, and their output current ripples cancel each other out, resulting in a ripple current much smaller than that of a single-phase Buck. This reduces the requirements for the output filter and decreases the size and cost of passive components.

[0015] (2) By adopting a parallel topology, this invention allows each phase to carry half of the current under the same total output power, enabling the selection of smaller current-rated switching transistors and inductors. This results in superior switching speed and on-resistance, which helps improve overall efficiency. At the same time, smaller magnetic components and capacitors contribute to the miniaturization of the system.

[0016] (3) By adopting an interleaved parallel topology, the control unit can detect the abnormality and take protective measures when one of the paths fails, while the other path can continue to work, ensuring that the power generation system is not completely paralyzed and greatly improving the reliability of the task.

[0017] (4) By adopting an interleaved parallel topology, the present invention effectively doubles the switching frequency by using two-phase parallel connection, which makes the system respond faster to load changes and helps maintain the stability of the output voltage. Attached Figure Description

[0018] Figure 1 This is an overall system block diagram of the high-voltage generator controller of the present invention; Figure 2 This is the mathematical model of the Buck circuit of the present invention; Figure 3 This is a structural diagram of the Buck circuit voltage and current dual closed-loop control system of the present invention; Figure 4 This is a schematic diagram of the power circuit of the high-voltage generator controller of the present invention; Figure 5 This is a schematic diagram of the drive circuit for the high-voltage generator controller of the present invention; Figure 6 This is a schematic diagram of the voltage and current sampling circuit of the high-voltage generator controller of the present invention; Detailed Implementation To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in detail below with reference to the accompanying drawings.

[0019] The mathematical model of a Buck circuit is as follows: Figure 2 As shown, without considering the parasitic inductance of inductors and capacitors, the circuit equations can be listed as shown in equations (1-1) and (1-2) respectively when S is turned on and off.

[0020]

[0021] in, The voltage across the inductor is For inductor current, For the input bus voltage, Where L is the output voltage, C is the inductance value, and R is the output filter capacitor value.

[0022] When the Buck circuit operates in CCM mode, the switching cycle averaging method is used to average the switching cycles of each parameter in the above equation, letting the duty cycle of switch S be Duty. Based on the volt-second area balance principle, we can obtain:

[0023] The relationship between the input voltage and the output voltage can be expressed as:

[0024] To better control the current and output voltage of the Buck circuit's main loop, this invention employs a dual closed-loop control system with an inner current loop and an outer voltage loop. The structure of the dual closed-loop voltage and current control system is as follows: Figure 3 As shown.

[0025] The voltage loop controls the output voltage of the Buck circuit, ensuring that the output voltage accurately and stably tracks the given reference value. The current loop controls the inductor current of the Buck circuit and provides dynamic response and stability indicators through direct current control. The output voltage Vo is compared with the output voltage reference value Vref and used as the input to the voltage loop PI regulator. The output of the voltage loop PI regulator is used as the current loop inductor current reference value iref. iref is compared with the inductor current iL and used as the input to the current loop PI regulator. After passing through the current loop PI regulator, a modulation signal is output. This signal is then processed by a PWM pulse width modulator to generate a PWM signal with the corresponding duty cycle, thereby making the controller output follow the voltage reference value Vref.

[0026] Specifically, such as Figure 1 As shown, the high-voltage generator controller of the present invention with a two-phase interleaved parallel Buck topology includes a power circuit and a control system.

[0027] Power circuits such as Figure 4 As shown: The bus voltage output by the generator through the three-phase bridge rectifier circuit enters two Buck circuits after passing through the bus support capacitor Cin. The first Buck branch consists of switching transistors S1 and S2 and inductor L1, and the second Buck branch consists of switching transistors S3 and S4 and inductor L2. The output terminals of the two Buck circuits are connected to the positive terminal of the output filter capacitor Co. After being filtered by the output capacitor Co, the output supplies power to the load.

[0028] The two-phase Buck parallel power circuit includes a first Buck branch, a second Buck branch, a bus support capacitor Cin, and an output filter capacitor Co. The first Buck branch includes switching transistors S1 and S2, and inductor L1. The second Buck branch includes switching transistors S3 and S4, and inductor L2. The bus support capacitor Cin is connected in parallel between the positive and negative terminals of the bus voltage. The drain of switching transistor S1 is connected to the positive terminal of the bus voltage, and the source of switching transistor S1 is connected to one end of inductor L1 and the drain of switching transistor S2. The source of switching transistor S2 is connected to the bus voltage. The negative terminal; the other end of inductor L1 is connected to the positive terminal of output filter capacitor Co. The output voltage is filtered by output capacitor Co and then connected to the positive terminal of the load; the drain of switching transistor S3 is connected to the positive terminal of the bus voltage, and the source of switching transistor S3 is connected to one end of inductor L2 and the drain of switching transistor S4; the source of switching transistor S4 is connected to the negative terminal of the bus voltage; the other end of inductor L2 is connected to the positive terminal of output filter capacitor Co. The output voltage is filtered by output capacitor Co and then connected to the positive terminal of the load; the source of switching transistor S2 and the source of switching transistor S4 are connected together as the negative terminal of the load and are also grounded.

[0029] The control system generates two PWM signals with a phase difference of 180°. The first PWM signal is connected to the gates of switching transistors S1 and S2, and the second PWM signal is connected to the gates of switching transistors S3 and S4.

[0030] Control System: The control system includes a voltage and current sampling circuit, a sampling and conditioning circuit, a DSP minimum system circuit, and a MOSFET drive circuit. Voltage and Current Sampling Circuit: This circuit samples the bus voltage, the output voltage of the two-phase Buck parallel power circuit, and the inductor current in the first and second Buck branches, sending the samples to the sampling and conditioning circuit. The sampling and conditioning circuit processes the input bus voltage, output voltage, and inductor current, then transmits the signals to the DSP for further processing. The DSP minimum system circuit implements A / D conversion of current and voltage, a dual closed-loop voltage and current control algorithm, and protection functions. It also generates two sets of PWM signals with dead time and a 180° phase difference. PWM1 and PWM2 signals are amplified by the drive circuit and ultimately drive the gates of MOSFETs S1~S4.

[0031] Voltage and current sampling circuits, such as Figure 5 As shown, voltage sampling uses a resistor divider method. The input bus voltage or output voltage is divided by a resistor and then enters an isolation differential operational amplifier to obtain a set of differential signals. The differential signals are then processed by a sampling and conditioning circuit before entering the DSP. Current sampling uses a current sensor method. The inductor current is converted into a voltage signal by a current sensor and then processed by a sampling and conditioning circuit before entering the DSP.

[0032] MOSFET drive circuit, such as Figure 6As shown, the TI UCC21521 driver chip is selected. This driver chip is an isolated chamber dual-channel gate driver with a peak pull-up current of 4A and a peak pull-down current of 6A. It is used to drive power MOSFETs, IGBTs, and SiC MOSFETs up to 5MHz, and features best-in-class propagation delay and pulse width distortion, with a propagation delay of 19ns and a pulse width distortion of 5ns. A dual-supply configuration is used to ensure reliable switching of the SiC MOSFETs. The driver can be configured as two low-side drivers, two high-side drivers, or one dead-time programmable half-bridge driver. As a fail-safe mechanism, a primary-side logic fault will force both outputs to a low level, preventing common-mode conduction.

[0033] Working process: After the system is powered on, the control system starts and outputs a PWM signal. When the generator is driven to rotate by the prime mover, the bus voltage is obtained through the three-phase bridge rectifier circuit. The closed-loop control system of the two-phase interleaved parallel Buck circuit continuously adjusts the PWM duty cycle so that the generator controller output voltage can be stabilized at 270V no matter how the speed changes.

[0034] Redundancy Strategy: The control system can be configured to monitor the output current of both Buck branches. If an abnormal current is detected in one branch, the controller can shut down the PWM output of the faulty branch and issue an alarm signal. Simultaneously, the system automatically enters single-phase operating mode, increasing the PWM duty cycle of the other normal branch to maintain a 270V output, but the maximum output power will be reduced accordingly.

[0035] This invention discloses a high-voltage generator controller based on a two-phase interleaved parallel Buck topology, comprising a power circuit and a control system. The power circuit employs two parallel Buck circuits to achieve a stable DC output voltage across a wide generator speed range. The control system generates two PWM signals with a 180° phase difference via a DSP. These signals, after passing through a MOSFET driver circuit, drive the switching transistors of the two Buck circuits respectively. By sampling the generator output voltage and inductor current, a dual closed-loop voltage-current control is employed to adjust the PWM signal duty cycle, thereby ensuring the generator controller output voltage meets requirements. This invention, through interleaved parallel technology, effectively reduces input and output current ripple, lowers the requirements for the input power supply and output filter capacitor, and improves system efficiency and power density.

[0036] The contents not described in detail in this specification are common knowledge to those skilled in the art.

Claims

1. A high-voltage generator controller based on a two-phase interleaved parallel Buck topology, characterized in that: Includes a two-phase Buck parallel power circuit and control system; The dual-phase Buck parallel power circuit has its input terminal connected to the bus voltage after three-phase bridge rectification, and its output terminal connected to the load. Under the control of the control system, the bus voltage is stepped down to achieve a stable DC voltage output by the controller under a wide speed range of the generator. The control system generates two PWM signals with a 180° phase difference to drive the switching transistors of the dual-phase Buck parallel power circuit; it samples the output voltage and inductor current of the dual-phase Buck parallel power circuit, and uses voltage and current dual closed-loop control to adjust the duty cycle of the PWM signals to ensure that the output voltage of the dual-phase Buck parallel power circuit meets the requirements.

2. A high-voltage generator controller based on a two-phase interleaved parallel Buck topology according to claim 1, characterized in that, The dual-phase Buck parallel power circuit includes a first Buck branch, a second Buck branch, a bus support capacitor Cin, and an output filter capacitor Co; The first Buck branch includes switching transistor S1, switching transistor S2, and inductor L1; The second Buck branch includes switching transistor S3, switching transistor S4, and inductor L2; The bus support capacitor Cin is connected between the positive and negative terminals of the bus voltage; the drain of the switching transistor S1 is connected to the positive terminal of the bus voltage, and the source of the switching transistor S1 is connected to one end of the inductor L1 and the drain of the switching transistor S2; the source of the switching transistor S2 is connected to the negative terminal of the bus voltage; the other end of the inductor L1 is connected to the positive terminal of the output filter capacitor Co, and the output voltage is connected to the positive terminal of the load after being filtered by the output capacitor Co. The drain of switch S3 is connected to the positive terminal of the bus voltage, and the source of switch S3 is connected to one end of inductor L2 and the drain of switch S4. The source of switch S4 is connected to the negative terminal of the bus voltage. The other end of inductor L2 is connected to the positive terminal of output filter capacitor Co. The output voltage is filtered by output capacitor Co and then connected to the positive terminal of the load. The source terminals of switching transistors S2 and S4 are connected and used as the negative terminal of the load, while also being grounded.

3. A high-voltage generator controller based on a two-phase interleaved parallel Buck topology according to claim 2, characterized in that, The control system generates two PWM signals with a phase difference of 180°. The first PWM signal is connected to the gates of switching transistors S1 and S2, and the second PWM signal is connected to the gates of switching transistors S3 and S4.

4. A high-voltage generator controller based on a two-phase interleaved parallel Buck topology according to claim 2, characterized in that, The control system includes a voltage and current sampling circuit, a sampling conditioning circuit, a DSP minimum system circuit, and a MOSFET driving circuit. Voltage and current sampling circuit: used to sample the bus voltage, the output voltage of the two-phase Buck parallel power circuit, and the inductor current in the first Buck branch and the second Buck branch, and send them to the sampling and conditioning circuit; Sampling and conditioning circuit: The bus voltage, output voltage of the two-phase Buck parallel power circuit and inductor current sampled by the voltage and current sampling circuit are conditioned and the conditioned signals are transmitted to the DSP minimum system circuit for processing. DSP minimum system circuit: realizes current-voltage A / D conversion, and generates two PWM signals with dead time and 180° phase difference based on the output voltage and inductor current using voltage and current dual closed-loop control; MOSFET drive circuit: The two PWM signals are amplified. The amplified first PWM signal is used to drive the switching transistors S1 and S2 of the first Buck branch, and the amplified second PWM signal is used to drive the switching transistors S3 and S4 of the second Buck branch.

5. A high-voltage generator controller based on a two-phase interleaved parallel Buck topology according to claim 4, characterized in that, The voltage and current sampling circuit includes a voltage sampling sub-circuit and a current sampling sub-circuit. The voltage sampling sub-circuit uses a resistor divider method to divide the bus voltage and the output voltage of the two-phase Buck parallel power circuit. Then, a set of differential signals is obtained through an isolation differential operational amplifier and sent to the sampling conditioning circuit. The current sampling sub-circuit uses a current sensor. The inductor currents in the first Buck branch and the second Buck branch are converted into voltage signals after passing through the current sensor and sent to the sampling and conditioning circuit.

6. A high-voltage generator controller based on a two-phase interleaved parallel Buck topology according to claim 4, characterized in that, The control system also includes a fault detection and redundancy control module, which is used to monitor the output current of the two Buck branches in real time; when a fault is detected in a Buck branch, fault information is sent to the DSP minimum system circuit. After receiving information that a Buck branch has failed, the DSP minimum system circuit stops sending PWM signals to the failed branch and adjusts the PWM duty cycle of the other normal branch to maintain the output voltage of the two-phase Buck parallel power circuit.

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