A low-cost resonant bus converter control method based on a single-chip microcomputer

Abstract

The application provides a low-cost resonant bus converter control method based on a single-chip microcomputer; after power-on, a digital control unit initializes a single-chip microcomputer internal clock, I / O port and PWM signal, and the bus converter enters a standby state; after receiving a remote start command, the digital control unit firstly judges a bus converter self-fault state, returns to the standby state if there is a fault, does not respond to the start command if there is no fault, and the bus converter enters a soft start process; the digital control unit sends out a driver control signal, which is amplified by a drive control unit to control the bus converter to complete the soft start; after entering a normal working state, the digital control unit judges the bus converter self-fault state again, and controls the resonant bus converter to enter the standby state if there is a fault. The application improves the reliability of the resonant bus converter.

Description

TECHNICAL FIELD

[0001] The present application relates to power conversion technology, in particular to the power supply resonant bus converter control technology considering communication function, which is applied to the power supply system of communication, guidance and electronic countermeasure equipment. BACKGROUND

[0002] With the large-scale application of distributed power supply system in radar and integrated radio frequency active array system, higher requirements are put forward for the power density, efficiency and cost performance of the bus converter in the distributed power supply system, and real-time monitoring and communication function are required; most of the existing high power density bus converters adopt hard switching circuit topology, and under the condition of high voltage input and high power output, the switching loss is greatly increased while the switching frequency is improved, which reduces the efficiency of the bus converter; and the existing bus converter basically adopts analog chip control, which needs to increase a communication control chip to realize real-time monitoring and communication function while improving the power density and efficiency, thereby increasing the system complexity; the existing digital converter adopts software shutdown mode, and the output port state may be transiently uncertain during the operation of the shutdown program, which further expands the fault of the resonant bus converter; the soft start mode of the existing bus converter uses PWM pulse width regulation, which is not suitable for the resonant bus converter topology. SUMMARY

[0003] The purpose of the present application is to provide a low-cost resonant bus converter control method based on a single-chip microcomputer.

[0004] The technical solution for achieving the purpose of the present application is a low-cost resonant bus converter control method based on a single-chip microcomputer, which realizes half-bridge resonant bus converter control through a digital control unit and a drive control unit, comprising:

[0005] After power-on, the digital control unit initializes the internal clock, I / O port and PWM signal of the single-chip microcomputer, and the bus converter enters standby state;

[0006] After receiving the remote start command, the digital control unit first judges the fault state of the bus converter itself, returns to standby state if there is a fault, and does not respond to the start command if there is no fault, and the bus converter enters soft start process;

[0007] The digital control unit sends out the driver control signal, which is amplified by the drive control unit to control the bus converter to complete soft start; after entering normal working state, the digital control unit judges the fault state of the bus converter itself again, and controls the resonant bus converter to enter standby state if there is a fault.

[0008] Furthermore, the digital control unit generates high-frequency complementary pulses with dead time, where PWM1 and PWM2 are complementary and amplified by the drive control unit to control the on / off state of the primary switching transistor, and PWM3 and PWM4 are complementary and amplified by the drive control unit to control the on / off state of the secondary synchronous rectifier transistor.

[0009] Furthermore, the digital control unit determines the fault status of the bus converter itself, that is, based on the input voltage V. in Output voltage V out Current I out and primary current signal I Lr The software will then make the judgment.

[0010] Furthermore, during the soft-start process, the duty cycles of PWM1, PWM2, PWM3, and PWM4 output by the digital control unit gradually increase from 10% to 100%, and the switching frequency f increases from the resonant frequency f... r Doubled down to the resonant frequency f r When the output capacitor voltage V out When the set output voltage is reached to 90%, the bus converter completes the soft start state and enters the normal operating state. The digital control unit output frequency is f. r The PWM1, PWM2, PWM3 and PWM4 signals.

[0011] Furthermore, the digital control unit detects the voltage Vout on the output capacitor and the primary-side current I. Lr It coordinates the change rate of the switching frequency f and the PWM duty cycle, thereby reducing the current stress on the primary-side switch and the peak current of the input power supply.

[0012] Furthermore, after entering normal operation, the digital control unit again judges the fault status of the bus converter itself. If there is a fault, it first sends out a drive control signal to shut down the output of the drive control unit and shut down the bus converter; then it delays the shutdown of the internal PWM clock, stops the output of PWM1, PWM2, PWM3 and PWM4 signals, enters the standby state, and waits for the next start control signal.

[0013] A low-cost resonant bus converter control system based on a microcontroller is disclosed. Based on the aforementioned resonant bus converter control method, low-cost resonant bus converter control based on a microcontroller is achieved.

[0014] Compared with existing technologies, the significant advantages of this invention are: 1) The circuit is simple, improving the power density and efficiency of the bus converter while effectively simplifying the design and debugging of the resonant bus converter. 2) Controlled soft start and rapid fault protection methods effectively improve the reliability of the resonant bus converter. 3) Power control is implemented by a low-cost microcontroller, which also provides real-time monitoring and communication functions, significantly reducing production costs. Attached Figure Description

[0015] Figure 1 This is a connection diagram for a low-cost resonant bus converter based on a microcontroller.

[0016] Figure 2 This is a diagram showing the generation and control connection of the drive signal for the resonant bus switch.

[0017] Figure 3 This is a block diagram of the controlled soft start and fast fault protection control logic for the resonant bus converter.

[0018] Figure 4 This is a timing diagram of the soft start and fast fault protection of the resonant bus converter. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0020] This invention simplifies the design of resonant bus converters, improves the power density and efficiency of the bus converter through resonant control methods, achieves efficient soft start and rapid fault protection, and utilizes a general-purpose microcontroller to realize real-time monitoring and communication functions, thereby reducing hardware costs.

[0021] A low-cost resonant bus converter based on a microcontroller includes a primary half-bridge 101 composed of switching transistors V1 and V2, and a transformer T1 and a capacitor C. r Magnetizing inductance L p and leakage L r The resonant unit 102 consists of a rectifier diode V SR1 and V SR2 The system comprises a synchronous rectification unit 103, a digital control unit 104 composed of a microcontroller D1, and a drive control unit 105 composed of drivers N1 and N2. The resonant unit L... p L r and C r The primary current I Lr Sine-s ... ab A suitable phase difference is formed, enabling the primary-side switches V1 and V2 to achieve zero-voltage turn-on, and the secondary synchronous rectifier V... SR1 V SR2 Achieve zero-current shutdown.

[0022] A control method for a low-cost resonant bus converter based on a microcontroller includes resonant high-frequency drive pulse generation, soft start of the resonant bus converter, and fast fault protection control.

[0023] (1) Generation of resonant high-frequency driving pulse

[0024] The microcontroller D1, remotely controlled by the host computer D2, generates high-frequency complementary pulses with a 50% duty cycle and a dead time. The primary switching transistor drive pulses PWM1 and PWM2 are complementary, as are the secondary synchronous rectifier transistor drive pulses PWM3 and PWM4. The pulse frequency and dead time can be determined based on the operating state of the resonant bus converter and the internal resonant unit L of the converter. r and C r By adjusting and setting the resonance parameters, the converter can be designed to achieve optimal efficiency.

[0025] (2) Soft start and fast fault protection control of resonant bus converter

[0026] After power-on, microcontroller D1 initializes its internal clock, I / O ports, and PWM. Upon completion, the bus converter enters standby mode. Microcontroller D1 waits for a remote start command from the host computer D2. If the remote start command is sent to microcontroller D1, it first checks the bus converter's fault status. If a fault is found, it returns to standby mode and does not respond to the start command. If no fault is found, the bus converter enters a soft-start process. After entering normal operating mode, the digital control unit again checks the bus converter's fault status. If a fault is found, it controls the resonant bus converter to enter standby mode. Specifically:

[0027] The microcontroller D1 first sends out the driver control signals EN_P and EN_S, and then sends out two complementary PWM1 and PWM2 signals with dead time, and the corresponding PWM3 and PWM4 signals. The duty cycle of the sent PWM signals gradually increases from 10% to 100%, and the signal frequency f increases from the resonant frequency 2f. r Gradually decrease to the resonant frequency f r Detect the voltage Vout on the output capacitor and the primary side current I. Lr This coordinates the rate of change of the switching frequency f and the PWM duty cycle, reduces the current stress on the primary-side switch and the peak current of the input power supply, and controls the current I in the resonant cavity. Lr Peak value.

[0028] When the output capacitor voltage V out When the set output voltage reaches 90%, the bus converter completes the soft start state and enters the normal operation state.

[0029] After normal operation, the microcontroller D1 continuously monitors the input voltage Vin, the voltage Vout across the output capacitor, the output current Iout, and the primary side current I. LrThe system determines whether a power supply malfunction has occurred. When a malfunction occurs, microcontroller D1 first cuts off the primary drive control signal EN_P and the synchronous rectification drive control signal EN_S to shut down drivers N1 and N2, quickly cuts off the outputs of SW1, SW2, SR1, and SR2, and rapidly shuts off the resonant cavity current I. Lr To achieve rapid protection of the bus converter and prevent further failure of the resonant bus converter caused by the transient uncertainty of the output port state due to the operation of the internal shutdown program of the microcontroller D1; then shut down the internal PWM generation timer, shut down PWM1, PWM2, PWM3, and PWM4, and enter standby mode.

[0030] Example

[0031] To verify the effectiveness of the present invention, the following experimental design was conducted.

[0032] A circuit connection diagram of a resonant bus converter is shown below. Figure 1 As shown, the control chip D1 in the circuit can be selected from STMicroelectronics' STM32F103C8T6 chip, with an input voltage range of 240V to 360V, using a half-bridge topology. Drivers N1 and N2 can be selected from TI's UCC27524 chip, and the CAN bus can be selected from the ADM3053 chip. The primary-to-secondary voltage ratio of the bus converter is 22:3; when the input voltage is 300V, the output voltage is 42V. The circuit resonant unit C... r Choose 20nF, L r The transformer T1 has an 8.6μH primary winding and a secondary winding of 11 turns, a magnetizing inductance of 120μF, a leakage inductance of 2.7μH, and a resonant frequency of 300kHz. The host computer D2 controls the microcontroller D1 via the CAN bus to start the resonant bus converter. Microcontroller D1 sends control signals to turn on drivers N1 and N2. Microcontroller D1 then delays and starts its internal PWM timer, outputting complementary PWM1 and PWM2 signals to driver N1. Driver N1 amplifies the drive signals and sends them to the primary-side switching transistors V1 and V2. Microcontroller D1 also outputs control signals SR1 and SR2 to driver N2, which amplifies the drive signals and sends them to the synchronous rectifier diode V1. SR1 and V SR2 .

[0033] The controlled soft-start method for the resonant bus converter involves the following steps: First, after microcontroller D1 is powered on, its internal clock, I / O ports, and PWM clock are initialized. After completion, the bus converter enters standby mode. The microcontroller waits for a remote start command from the host computer D2 via CAN communication. If the remote start command is sent to microcontroller D1, D1 determines the bus converter's fault status. If a fault is detected, it returns to standby mode and does not respond to the start command. If no fault is detected, microcontroller D1 sends a control signal to open drivers N1 and N2. Figure 4At time t0, the microcontroller's D1 delay starts the internal PWM timer, sending out two drive signals with dead time, thus entering the soft-start phase. Figure 4 At time t1, microcontroller D1 outputs complementary PWM1 and PWM2 signals to driver N1. Driver N1 isolates and amplifies the drive signals and sends them to the primary-side switching transistors V1 and V2. Microcontroller D1 outputs drive signals PWM3 and PWM4 to driver N2. Driver N2 amplifies the drive signals and sends them to the synchronous rectifier transistor V1. SR1 and V SR2 The duty cycles of PWM1, PWM2, PWM3, and PWM4 gradually increase from 10% to 100%, and the switching frequency f increases from the resonant frequency f. r (Internal resonant unit C of the converter) r and L r The natural frequency gradually decreases to twice the resonant frequency f. r Detect the voltage Vout on the output capacitor and the primary side current I. Lr This coordinates the rate of change of the switching frequency f and the PWM duty cycle, reducing the current stress on the primary-side switch and the peak current of the input power supply. When the output capacitor voltage V... out When the set output voltage is reached to 90%, the bus converter completes the soft start state and enters the normal operating state. The output frequency of the microcontroller D1 is the resonant frequency f. r The PWM1, PWM2, PWM3 and PWM4 signals, such as Figure 4 At time t2, the input voltage V is... in Output voltage V out Current I out and primary current signal I Lr The signals from the sampling circuit enter the microcontroller D1. Microcontroller D1 converts the voltage and current signals through analog-to-digital conversion, and then performs software-based fault detection. If a fault occurs, microcontroller D1 first sends out drive control signals EN_P and EN_S to shut down drivers N1 and N2. Figure 4 At time t3, the bus converter is quickly shut down to prevent further failure of the resonant bus converter caused by the transient uncertainty of the output port state due to the operation of the internal shutdown program of the microcontroller D1, thus protecting the bus converter from damage. The internal PWM clock is then delayed, stopping the output of PWM1, PWM2, PWM3, and PWM4 signals, and entering standby mode. Figure 4 At time t4, wait for the next start control signal and restart the soft start process. Figure 4 Mid-T5 time.

[0034] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0035] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these modifications and improvements all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A low-cost control method for a resonant bus converter based on a microcontroller, characterized in that, The control of the half-bridge resonant bus converter is achieved through a digital control unit and a drive control unit, including: After power-on, the digital control unit initializes the microcontroller's internal clock, I / O ports, and PWM signals, and the bus converter enters standby mode. After receiving the remote start command, the digital control unit first determines the fault status of the bus converter itself. If there is a fault, it returns to the standby state and does not respond to the start command. If there is no fault, the bus converter enters the soft start process. The digital control unit sends out the driver control signal, which is amplified by the driver control unit to control the bus converter to complete the soft start. After entering the normal working state, the digital control unit judges the fault status of the bus converter itself again. If there is a fault, it controls the resonant bus converter to enter the standby state. in: The digital control unit generates high-frequency complementary pulses with dead time, where PWM1 and PWM2 are complementary and are amplified by the drive control unit to control the on / off state of the primary switching transistor, and PWM3 and PWM4 are complementary and are amplified by the drive control unit to control the on / off state of the secondary synchronous rectifier transistor. During the soft start process, the duty cycles of PWM1, PWM2, PWM3, and PWM4 output by the digital control unit gradually increase from 10% to 100%, and the switching frequency... f From the resonant frequency f r Doubled down to resonant frequency f r When the output capacitor voltage V out When the set output voltage is reached (90%), the bus converter completes the soft-start state and enters normal operation. The digital control unit output frequency is... f r The PWM1, PWM2, PWM3 and PWM4 signals; After entering normal operation, the digital control unit once again judges the fault status of the bus converter itself. If there is a fault, it first sends out a drive control signal to shut down the output of the drive control unit and shut down the bus converter; then it delays the shutdown of the internal PWM clock, stops the output of PWM1, PWM2, PWM3 and PWM4 signals, enters standby mode, and waits for the next start control signal.

2. The low-cost resonant bus converter control method based on a single-chip microcomputer according to claim 1, characterized in that, The digital control unit determines the fault status of the bus converter itself, that is, based on the input voltage V. in Output voltage V out Current I out and primary current signal I Lr， Perform software-based judgment.

3. The low-cost resonant bus converter control method based on a microcontroller according to claim 1, characterized in that, The digital control unit detects the voltage Vout on the output capacitor and the primary-side current I. Lr Coordinated control of switching frequency f The rate of change of PWM duty cycle reduces the current stress on the primary-side switch and the peak current of the input power supply.

4. A low-cost resonant bus converter control system based on a microcontroller, characterized in that, Based on the resonant bus converter control method according to any one of claims 1-3, a low-cost resonant bus converter control based on a microcontroller is realized.

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