Bidirectional On-Board Charger Using Shared PFC Bridge Arms
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing on-board chargers for electric vehicles are limited in their ability to charge a power battery and supply power to an external load simultaneously, resulting in poor applicability and high circuit costs.
Innovation Solution
A bidirectional on-board charger is designed to charge a power battery using a three-phase alternating current power supply and supply power to an alternating current load using the same power battery, through a power factor correction circuit and a controller that manages switches to enable both forward charging and reverse discharging functions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the on-board charger is designed for forward charging only, then the charging function is simple and reliable, but the device cannot supply power to external loads, resulting in poor adaptability
Solution Approach 1:
The on-board charger is designed with bidirectional power flow capability, allowing it to perform both forward charging (AC to DC) and reverse discharging (DC to AC) functions using the same power conversion circuit. The controller switches between different working modes to enable the charger to adapt to different application scenarios, including vehicle charging and external load power supply, thereby achieving multi-functionality without significantly increasing circuit complexity
Solution Approach 2:
The controller dynamically adjusts the working mode of the power conversion circuit based on the operational requirements. By controlling the switching states of the bridge arms and power switches, the system can transition between charging mode, discharging mode, and different bridge arm configuration modes (first bridge arm mode, second bridge arm mode, third bridge arm mode), enabling adaptive response to different load and power supply conditions
2Reliability
If separate circuits are used for forward charging and reverse discharging, then each function is optimized, but the circuit cost increases significantly
Solution Approach 1:
The patent merges the forward charging circuit and reverse discharging circuit into a single bidirectional power conversion circuit. The same power switches, bridge arms, and control logic are used for both charging and discharging operations. By combining these functions into one integrated circuit, the system achieves both reliability through proven power conversion technology while significantly reducing circuit cost and component count compared to using separate dedicated circuits for each function
Solution Approach 2:
The power conversion circuit is designed as a universal circuit that can operate in multiple modes. The controller configures the bridge arms and power switches to enable the circuit to function as a rectifier during charging and as an inverter during discharging, eliminating the need for separate dedicated circuits and reducing overall system complexity and cost
3Adaptability or versatility
If a single bridge arm is used, then the circuit cost is reduced, but the charger cannot handle both single-phase and three-phase power inputs effectively
Solution Approach 1:
The controller dynamically reconfigures the bridge arm connections based on the input power phase type. For single-phase input, the controller activates specific bridge arms in a first configuration mode; for three-phase input, it switches to a second configuration mode that utilizes all three bridge arms. This dynamic reconfiguration allows the system to adapt to different power input types without requiring physically separate circuits for single-phase and three-phase operations, thereby achieving versatility while managing complexity through intelligent control
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
The bidirectional on-board charger significantly reduces circuit costs, enhances operational flexibility, and improves applicability by enabling simultaneous charging and power supply functions.
Implementation Method 1
a power factor correction (PFC) circuit, configured to receive a single-phase alternating current or a three-phase alternating current provided by the three-phase alternating current power supply, or configured to receive a direct current provided by the power battery
Implementation Method 2
The bidirectional on-board charger is compatible with a forward charging function of charging a power battery and a reverse discharging function of supplying power to an alternating current load
Data Source
AI summary
A bidirectional on-board charger includes a direct current bus, two bus capacitors, a power factor correction circuit, and a controller. The power factor correction circuit includes: a first bridge arm; and three second bridge arms, separately connected in series between the positive electrode and the negative electrode of the direct current bus. The controller is configured to: control the first switch (K1) to be turned off, and control at least one of the second bridge arms to output a direct current to charge a power battery; or control the first switch (K1) to be turned on, and control a midpoint of at least one of the second bridge arms to output an alternating current to supply power to an alternating current load. A Vehicle power system and an electric vehicle are further disclosed. The charger reduces circuit costs.