Motor Control Apparatus Thermal Management
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Solution Overview
Problem
Conventional motor control apparatuses require a low allowable temperature and long power holding time to ensure performance at the next start time, leading to increased dark current during motor shutdown, which consumes battery power unnecessarily.
Innovation Solution
A motor control apparatus that minimizes power self-holding time by estimating temperature rise based on current square values and first-order lag response, using an overheat protection map to determine when performance assurance conditions are met, allowing for early termination of power self-holding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the allowable temperature value is set low and the power holding time is extended to ensure performance at the next start time, then the motor performance is improved, but the dark current increases and battery power is consumed unnecessarily
Solution Approach 1:
The patent changes the parameter for determining power holding termination from a fixed temperature threshold to a dynamic evaluation based on the sum of temperature rises. By calculating the cumulative temperature increase during operation and comparing it against a threshold, the system can accurately determine when the motor has cooled sufficiently, avoiding both premature termination and excessive holding time.
Solution Approach 2:
The patent implements a feedback mechanism where the control unit continuously monitors the sum of temperature rises and uses this information to dynamically adjust the power holding duration. The system feeds back the temperature condition to the power holding control, enabling intelligent termination decision-making that balances performance assurance with energy conservation.
2Temperature
If the power holding time is extended to allow sufficient cooling, then the motor temperature is reduced, but the time duration with dark current flow increases
Solution Approach 1:
The patent transforms the temperature control approach by using the sum of temperature rises as the control parameter instead of absolute temperature. This parameter change enables the system to track the thermal state more efficiently and determine the exact moment when cooling is sufficient, optimizing the balance between temperature reduction and time duration.
3Object-affected harmful factors
If a fixed low temperature threshold is used for termination, then overheat protection is ensured, but the next start performance may be compromised due to insufficient cooling time
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing the threshold value for the sum of temperature rises during the motor operation phase. This threshold is determined based on the motor's thermal characteristics and cooling performance, allowing the system to make accurate termination decisions without requiring extended holding time or risking insufficient cooling.
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
This approach ensures required performance at the next start time while reducing power self-holding time, minimizing dark current and battery consumption.
Implementation Method 1
a temperature rise estimation section that estimates at least one temperature rise based on a square value of current flowing through the motor, the drive circuit, or the power supply circuit
Implementation Method 2
a temperature rise estimation section that estimates at least one temperature rise based on a square value of current flowing through the motor, the drive circuit, or the power supply circuit, or a first-order lag response of a time average of an integrated value of the current
Data Source
AI summary
A self-holding termination determination section has an overheat protection map that defines a relationship between a current value and a maximum temperature of a protected portion to which a current value is applied, and sets a limit temperature corresponding to a required current value at next start time based on the map. The self-holding termination determination section calculates, as an evaluation temperature, temperature obtained by adding a performance assurance upper limit temperature, which assures output performance of a motor at the next start time, to the sum of temperature rises. In a next time performance determination process, if the evaluation temperature for all protected portions has fallen below the limit temperature, the self-holding termination determination section determines that a performance assurance condition is met, and terminates power self-holding based on at least the fact that the performance assurance condition is met.