Motor-Assisted Power Converter for Wide Battery Charging Voltage
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Solution Overview
Problem
Existing power converters struggle to efficiently charge batteries with varying nominal voltages, as they often require a wide output voltage range and can exceed the maximum voltage capabilities of the charger, leading to inefficiencies and potential damage to semiconductor switching elements.
Innovation Solution
A power converter system that includes a charger, an inverter, and a motor with three star-connected coils, utilizing switching units and a controller to convert AC power to DC power, and using the motor and inverter to increase the voltage of the DC power output beyond the charger's maximum capacity, thereby widening the output voltage range without a step-up circuit and reducing the stress on semiconductor switching elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the charger is designed to output high voltage to charge batteries with different nominal voltages, then the adaptability is improved, but the semiconductor switching elements in the charger are subjected to excessive voltage stress and may be damaged
Solution Approach 1:
The patent introduces an inverter and motor as intermediary components between the charger and the battery. The charger outputs DC power at a safe voltage level, which is then converted to AC power by the inverter, and subsequently converted back to DC power at the required high voltage level by the motor acting as a generator. This intermediary conversion process protects the charger's semiconductor switching elements from excessive voltage stress while enabling the system to charge batteries with different nominal voltages.
Solution Approach 2:
The patent replaces the traditional electrical voltage boosting method (which would require high-voltage semiconductor switching elements in the charger) with a mechanical energy conversion system. The motor, when driven by the inverter, functions as a generator to convert mechanical energy back into electrical energy at a higher voltage level. This mechanical substitution allows the charger to operate at safe voltage levels while still achieving the required high output voltage for charging various battery types.
2Adaptability or versatility
If a step-up circuit is added to increase the output voltage range, then the adaptability is improved, but the device complexity increases
Solution Approach 1:
The patent utilizes the motor and inverter, which are already present in the power converter system for motor drive functions, to also serve as a voltage boosting mechanism for battery charging. By controlling the motor to operate as a generator, the system can convert DC power from the charger into AC power via the inverter, and then back into DC power at a higher voltage level. This multi-functional use of existing components avoids the need for additional step-up circuitry, thereby maintaining system simplicity while expanding the output voltage range to accommodate batteries with different nominal voltages.
3Productivity
If the charger is designed for maximum power output, then the productivity is improved, but the semiconductor switching elements are subjected to higher stress and reliability decreases
Solution Approach 1:
The inverter and motor-generiator combination serve as intermediary devices that enable the charger to operate at its maximum power output capability without exposing its semiconductor switching elements to excessive voltage stress. The charger converts AC power to DC power at a safe voltage level, and the subsequent AC-DC conversion through the motor-generiator provides the additional voltage multiplication needed for high-power charging of various battery types. This intermediary approach allows the system to achieve high productivity while maintaining the reliability of the charger's semiconductor components.
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 system effectively supplies batteries with power exceeding the charger's maximum output voltage, widening the output voltage range and allowing the use of less expensive semiconductor switching elements in the charger, while ensuring the inverter's switching elements handle higher voltages, thus enhancing efficiency and reducing component stress.
Implementation Method 1
a charger (11) configured to convert input alternating current (AC) power into direct current (DC) power
Implementation Method 2
an inverter (51) connected to the battery and configured to be supplied with DC power that is output from the battery, and a motor (61) connected to the inverter and including three star-connected coils. The motor is configured to be supplied with AC power that is output from the inverter
Implementation Method 3
using the motor and inverter to increase the voltage of the DC power output beyond the charger's maximum capacity
Data Source
AI summary
A power converter includes a charger that converts AC power into DC power, a battery connected to the charger and supplied with DC power from the charger, an inverter connected to the battery and supplied with DC power from the battery, and a motor connected to the inverter and including three star-connected coils. The motor is supplied with AC power from the inverter. A positive conductor connects the charger to a positive electrode of the battery. A negative conductor connects the charger to a negative electrode of the battery. A first switching unit in the positive conductor connects the charger and the battery. A connection line connects a node between the charger and the first switching unit in the positive conductor to a neutral point of the motor. A second switching unit arranged in the connection line connects the positive conductor and the neutral point of the motor.