Charging Apparatus Current Segmentation for Low-Temperature Battery Heating
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Solution Overview
Problem
Current methods for maintaining power storage element performance at low temperatures, such as reducing switching frequency to increase ripple current and heat, lead to voltage fluctuations, damage to the element, and increased noise, without ensuring sufficient performance in electric vehicles operating at -25°C.
Innovation Solution
A charging and discharging device with a switching circuit and a control unit that generates separate control signals for adjusting the ripple and non-ripple components of the output current, allowing for efficient temperature rise of the power storage element without exceeding voltage limits or damaging the switching elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the switching frequency of the chopper circuit is reduced to increase ripple current and heat the power storage element, then the temperature of the power storage element is raised, but the voltage ripple of the power storage element increases causing voltage to exceed upper or lower limit values to damage the power storage element
Solution Approach 1:
The control signal is segmented into two independent components: a first control signal for adjusting the ripple component and a second control signal for adjusting the non-ripple component of the output current. This segmentation allows independent optimization of heating effect (through ripple current) and voltage stability (through non-ripple current control), resolving the contradiction between temperature rise and voltage stability.
Solution Approach 2:
The invention changes the control parameters by separately adjusting the amplitude and characteristics of ripple and non-ripple current components. By modifying these parameters independently, the system can increase ripple current for heating while simultaneously controlling non-ripple current to maintain voltage within safe limits, thus resolving the voltage stability issue.
2Temperature
If the switching frequency is reduced to increase ripple current, then the heating effect is enhanced, but the output current of the chopper circuit increases exceeding the allowable maximum current of switching elements to damage them
Solution Approach 1:
The output current is segmented into ripple and non-ripple components, each controlled by separate control signals. This allows the ripple component to be optimized for heating effect while the non-ripple component is controlled to ensure the total current does not exceed the maximum allowable current of switching elements, preventing damage.
Solution Approach 2:
The invention applies partial action by controlling only the necessary portion of current as ripple for heating, while the remaining portion is controlled as non-ripple current. This partial approach to ripple current generation achieves sufficient heating without causing excessive total current that would damage switching elements.
3Temperature
If the ripple current is increased to heat the power storage element, then the temperature is raised, but noise from components of the chopper circuit increases
Solution Approach 1:
The invention changes the control parameters by independently adjusting the ripple and non-ripple current components. By optimizing the ripple component parameters for minimal noise generation while maintaining sufficient heating effect, and controlling the non-ripple component separately, the system achieves temperature rise with minimized electromagnetic noise from chopper circuit components.
4Temperature
If the switching frequency is changed to increase ripple current, then the heating effect is enhanced, but the frequency of electromagnetic noise from the components of the chopper circuit fluctuates to cause harsh noise
Solution Approach 1:
The control signal is segmented into two independent components that can be adjusted separately. This segmentation allows the system to maintain a constant switching frequency (avoiding noise fluctuations) while still achieving effective heating through optimized ripple current control, thus resolving the contradiction between heating effectiveness and noise stability.
Solution Approach 2:
The invention introduces dynamic control of the two separate current components, allowing the ripple and non-ripple portions to be adjusted independently in response to temperature and noise conditions. This dynamic control enables maintaining constant switching frequency for noise stability while achieving effective heating through adaptive ripple current management.
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 solution effectively raises the temperature of power storage elements like secondary batteries or electric double layer capacitors, preventing damage and maintaining performance in low-temperature environments while minimizing noise and voltage fluctuations.
Implementation Method 1
a switching circuit, an input of which is connected to a power supply, the switching circuit adjusting an output current to a power storing unit connected to an output of the switching circuit
Data Source
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AI summary
A charging and discharging device includes a switching circuit 44, an input of which is connected to a power supply, the switching circuit 44 adjusting an output current IB to a power storing unit 60 connected to an output of the switching circuit 44, and a control unit 46 configured to generate an ON/OFF signal DGC to the switching circuit 44. The control unit 46 includes a temperature-rise control unit 70 configured to separately generate, based on a signal BTMP equivalent to the temperature of the power storing unit 60, a control signal FC for adjusting a ripple component of the output current IB and a control signal OFS for adjusting a non-ripple component of the output current IB and generates the ON/OFF signal DGC based on the control signal FC and the control signal OFS and outputs the ON/OFF signal DGC to the switching circuit 44.