AC Drive Thermal Regulation via DC Link Heater Resistor
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Solution Overview
Problem
AC drives operating in cold temperatures face challenges in thermal regulation to prevent condensation and maintain operational temperature ranges, as existing solutions are either inefficient or require additional components.
Innovation Solution
A thermal regulation apparatus using a heater resistor connected across the DC link, controlled by a temperature sensor and controller to provide heat when necessary, which also functions as a dynamic brake resistor to dissipate excess energy, allowing for independent control and efficient heat management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a separate heater resistor and dynamic brake resistor are provided, then thermal regulation and dynamic braking functions are both achieved, but device complexity and component quantity increase
Solution Approach 1:
The patent applies multi-functionality by enabling the dynamic brake resistor to serve dual purposes: dissipating regenerated energy during motor deceleration and providing thermal regulation during cold operation. The controller selectively activates the resistor for braking when DC link voltage exceeds a threshold or for heating when temperature sensors detect cold conditions, eliminating the need for a separate heater resistor and reducing overall system complexity
2Loss of energy
If a power resistor is added to dissipate excess energy, then energy dissipation capability is improved, but device complexity increases
Solution Approach 1:
The patent integrates energy dissipation functionality into the existing dynamic brake resistor, which is already required for handling regenerated energy during motor deceleration. The same resistor and switching mechanism are used to dissipate both regenerated energy and excess energy from cold operation, eliminating the need for a separate power resistor and simplifying the overall system architecture
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
Effectively maintains AC drive components within an operational temperature range, preventing condensation and ensuring reliable operation in cold environments without the need for additional components, while also providing dynamic braking functionality.
Implementation Method 1
The heater resistor acts as a heat source when power is provided to it
Implementation Method 2
the heater resistor also functions as a dynamic brake resistor
Data Source
AI summary
An apparatus for the thermal regulation of an AC drive for providing power to a motor includes a temperature sensor producing a signal indicative of temperature, a heater resistor connectable across a DC link of the AC drive, and a first switch. A controller is operable to monitor the temperature signal and control the first switch to provide power via the DC link to the heater resistor if the sensed temperature is below a predetermined setpoint.