Bidirectional DC/DC Converter Self-Start for DC Bus Voltage Build-Up
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Solution Overview
Problem
Existing DC/DC converters lack self-start capability and require additional components and complex control logic for black start operations, leading to inefficiencies and increased system complexity in energy storage systems.
Innovation Solution
A bidirectional DC/DC converter with a start circuit, inductor, and switch circuit that allows for self-start capability by controlling controllable switches to gradually establish high-voltage port voltage from a low-voltage port, utilizing buck and boost conversion modes to optimize voltage control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional precharging resistors and high-voltage DC contactors are added to enable black start operation, then the system can perform black start operations, but the device complexity and cost increase
Solution Approach 1:
The DC/DC converter is designed with self-start capability that allows it to autonomously establish DC bus voltage during black start operations without requiring external assistance or additional dedicated starting components. The converter independently completes the voltage building process through its own control circuitry and power switching devices.
Solution Approach 2:
The DC/DC converter is designed to perform multiple functions: normal power conversion operation and black start voltage establishment. By integrating the black start capability into the existing converter structure, the same device serves both routine operation and emergency starting purposes, eliminating the need for separate starting components.
2Reliability
If additional precharging resistors and high-voltage DC contactors are added to enable black start operation, then the system can perform black start operations, but the cost increases
Solution Approach 1:
The DC/DC converter is designed with self-start capability that allows it to autonomously establish DC bus voltage during black start operations without requiring external assistance or additional dedicated starting components. The converter independently completes the voltage building process through its own control circuitry and power switching devices.
Solution Approach 2:
The DC/DC converter is designed to perform multiple functions: normal power conversion operation and black start voltage establishment. By integrating the black start capability into the existing converter structure, the same device serves both routine operation and emergency starting purposes, eliminating the need for separate starting components.
3Device complexity
If the DC bus voltage is supplied using a direct-mounted battery, then the black start process is simplified, but the adaptability of connecting different batches and different types of batteries is reduced
Solution Approach 1:
The DC/DC converter can operate with different battery configurations by adjusting its voltage conversion ratio and control parameters. The converter adapts to different battery voltages and types by modifying its operating parameters, enabling flexible connection of various battery batches and types while maintaining proper DC bus voltage establishment.
4Productivity
If the voltage of the high-voltage port is established quickly, then the black start process is faster, but voltage spikes and system instability may occur
Solution Approach 1:
The DC/DC converter uses periodic pulse-width modulation (PWM) switching to build up the DC bus voltage in controlled stages. The switching devices operate in periodic cycles, gradually transferring energy from the low-voltage battery to the high-voltage DC bus, achieving both relatively fast voltage establishment and voltage stability through rhythmic energy transfer.
Solution Approach 2:
The control circuitry of the DC/DC converter continuously monitors the DC bus voltage and adjusts the switching duty cycle accordingly. This feedback mechanism ensures that the voltage builds up at an optimal rate, preventing overshoot and instability while maintaining efficient black start operation. The controller modulates the power transfer based on real-time voltage measurements.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables flexible and efficient voltage soft-start, decoupling system components, reducing costs and complexity by allowing the converter to establish DC bus voltage independently, enhancing adaptability and reliability during black start operations.
Implementation Method 1
an inductor having one end electrically connected to the other end of the start circuit... At the first working stage, the start circuit and the inductor perform buck conversion on the first voltage to obtain the voltage of the high-voltage port
Implementation Method 2
a start circuit having one end electrically connected to the low-voltage port, includes at least one controllable switch. When the bidirectional DC/DC converter starts from the low-voltage port, a voltage of the high-voltage port is established using the first voltage, by controlling the at least one controllable switch
Data Source
Figure 1a~1c
Figure 2a~2b
Figure 3~4
AI summary
The invention provides a bidirectional DC/DC converter, including: a low-voltage port (PortB) having a first voltage; a high-voltage port; a start circuit (A1) having one end electrically connected to the low-voltage port (PortB); an inductor (L1) having one end electrically connected to the other end of the start circuit (A1); and a switch circuit (A2) having both ends electrically connected to the high-voltage port and the other end of the inductor (L1), respectively. The start circuit (A1) includes at least one controllable switch. When starting from the low-voltage port (PortB), a voltage of the high-voltage port is established using the first voltage, by controlling the at least one controllable switch. The bidirectional DC/DC converter has a self-start capability, and the voltage soft start way is flexibly controllable.