Robot Motor Stator Heating in Cold Environments
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Solution Overview
Problem
Industrial robots are limited to operating within a narrow temperature range of +5°C to 50°C, making them unsuitable for cold environments, as existing methods require either energy-intensive warm-up movements or external heating, which can cause wear and increase costs.
Innovation Solution
Applying a stator current in the d-direction of the rotor, generating heat through resistance losses in the motor, which is then transferred to the gears and lubrication via thermal convection, eliminating the need for additional heating equipment and minimizing mechanical stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If warm-up movements are executed to heat the drive train, then the temperature of the robot components is improved, but mechanical wear increases and energy consumption increases
Solution Approach 1:
The patent replaces mechanical warm-up movements with electrical current application to the stator coils. Instead of using the motor's mechanical operation to generate heat through friction and energy dissipation, the invention directly applies electrical current to heat the stator windings, thereby heating the motor and drive train components without mechanical wear.
Solution Approach 2:
The motor's stator coils serve dual purposes: they are both functional components for motor operation and heating elements for warm-up. By applying current to the stator coils, the motor heats itself and the surrounding drive train components, eliminating the need for separate heating equipment or mechanical warm-up cycles.
2Temperature
If external local heating is added to warm up the drive train, then the temperature of the robot components is improved, but device complexity and installation cost increase
Solution Approach 1:
The stator coils of the motor are designed to perform multiple functions: they serve as both the electromagnetic windings necessary for motor operation and as heating elements for warm-up. This multi-functionality eliminates the need for separate external heating equipment, reducing device complexity and installation costs.
Solution Approach 2:
The heating function is merged with the motor structure itself. The stator coils that are already present in the motor are utilized for both motor operation and heating purposes, combining two functions into a single integrated system rather than adding separate heating components.
3Temperature
If warm-up movements are executed to heat the drive train, then the temperature of the robot components is improved, but energy consumption increases
Solution Approach 1:
The patent replaces energy-consuming mechanical warm-up movements with direct electrical heating of the stator coils. This substitution reduces energy consumption by eliminating the inefficiencies of mechanical friction and motion required for warm-up, using instead direct resistive heating which is more energy-efficient for thermal generation.
4Adaptability or versatility
If the robot operates in cold environments below +5°C, then the operational range is improved, but the reliability of sealings and lubrication deteriorates
Solution Approach 1:
The patent applies preliminary heating action to the motor and drive train components before the robot begins operation in cold environments. By heating the stator coils and allowing the heat to transfer to the gears, sealings, and lubrication, the system ensures that critical components are at appropriate temperatures before operational stresses are applied, maintaining reliability while expanding operational temperature range.
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 method allows for rapid and efficient heating of the drive train without additional equipment, protecting the robot's mechanical structure and reducing operational costs, while maintaining the robot's functionality in cold conditions.
Implementation Method 1
the current through the stator windings will heat up the stator due to electrical resistance losses
Implementation Method 2
a current is applied to at least one phase stator coil of the motor if the motor stands still creating a directed magnetic flux which interacts with the rotor in such a way that the resulting torque will be close to zero
Implementation Method 3
which will create a favourable warm-up of the motor. In this way the invention enables to heat up the drive trains very quickly
Data Source
Figure 1~3
Figure 2
Figure 4~5
AI summary
The invention proposes a method for heating of robots in cold environments, whereby the robot possesses permanent magnet brushless or three-phase synchronous motors (1) with three motor phases comprising three stator coils (L1, L2, L3) connected to an inverter (3) controllable by a control-unit (4) and with a rotor with permanent magnet excitation (2). A current is applied to at least one phase respectively stator coil (L1, L2, L3) of the motor (1) if the motor stands still creating a directed magnetic flux (F) which interacts with the permanent magnets of the rotor in such a way that the resulting torque will be close to zero. Further the invention proposes a system for heating of robots in cold environments whereby the inverters (3) and motors (1) in standstill are used to heat up the critical drive train components, where by at least one supervisory-control-unit (5) monitors the motor temperature in order to avoid overheating.