Electronically Commutated Motor Current Regulation
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Solution Overview
Problem
Existing electronically commutated motors for fans in the telecommunications industry face challenges with high-frequency conducted interference, leading to disruptions such as background noise during phone calls, and require solutions to reduce low-frequency conducted interference while maintaining efficient power usage.
Innovation Solution
The motor design incorporates a current regulator that reduces fluctuations in the average current consumed by the output stage, using a microprocessor-controlled system with a current measuring resistor and PWM signals to manage the commutation process, thereby minimizing current peaks and improving power supply efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a conventional converter with smoothing choke is used to control the motor, then the system can operate, but the intermediate circuit current causes resonance phenomena and conducted interference that disrupt communications
Solution Approach 1:
The patent removes the converter and smoothing choke from the system entirely. Instead of using a conventional AC-to-DC converter with intermediate circuit, the invention uses a DC battery source directly connected to the inverter, extracting and eliminating the problematic intermediate circuit that causes resonance and conducted interference.
Solution Approach 2:
The patent introduces a current regulator as an intermediary control element between the battery and inverter. This regulator measures the intermediate circuit current and adjusts the inverter's switching duty cycle to maintain constant average current, thereby eliminating resonance phenomena without requiring a smoothing choke.
2Stability of the object's composition
If a smoothing choke is added to suppress resonance, then resonance phenomena are reduced, but the control process is delayed and system complexity increases
Solution Approach 1:
The patent extracts and eliminates the smoothing choke from the system. By removing this passive component entirely and replacing it with active current regulation through the controller, the system achieves resonance suppression without the time delays and complexity associated with large inductive components.
Solution Approach 2:
The patent replaces the mechanical/passive smoothing choke with an electronic control system. The controller uses software-based current measurement and PWM duty cycle adjustment to achieve the same smoothing effect that would require a large physical inductor, thereby eliminating the control delays inherent in passive choke-based systems.
3Reliability
If damping resistors or active damping are used to maintain stability in the resonance area, then system stability is improved, but device complexity and energy loss increase
Solution Approach 1:
The patent removes damping resistors and the need for active damping control algorithms entirely. By eliminating the intermediate circuit with its resonance-prone LC network, the system achieves inherent stability without requiring additional damping components that would dissipate energy as heat.
Solution Approach 2:
The patent enables the system to self-regulate through the current regulator's feedback control. The controller automatically adjusts the inverter's PWM duty cycle based on measured intermediate circuit current, maintaining stability and preventing resonance without requiring external damping resistors or complex active damping control systems.
4Use of energy by moving object
If the intermediate circuit current is regulated to maintain cos φ = 1, then power factor is improved, but the current fluctuations and peaks still cause conducted interference
Solution Approach 1:
The patent implements a feedback control system where the controller continuously measures the intermediate circuit current and adjusts the inverter's PWM duty cycle accordingly. This closed-loop current regulation maintains constant average current, eliminating the current peaks and fluctuations that cause conducted interference while preserving efficient power usage.
Solution Approach 2:
The patent dynamically changes the PWM duty cycle parameter of the inverter based on the measured intermediate circuit current. By continuously adjusting this control parameter, the system maintains optimal operating conditions with constant average current, eliminating interference without sacrificing power factor performance.
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 significantly reduces conducted interference, ensuring compliance with ETSI standards and enhancing the operational reliability of fans in noisy environments by stabilizing the power supply and reducing electromagnetic emissions.
Implementation Method 1
an intermediate circuit voltage UZK is applied to an intermediate circuit capacitor 22... a current measuring resistor 36
Implementation Method 2
The output stage 18 is used to power the winding arrangement 16... controlled by a microprocessor or microcontroller... PWM signals
Implementation Method 3
An intermediate circuit voltage UZK is applied to an intermediate circuit capacitor 22
Implementation Method 4
an electronically commutated motor 10 with a rotor 12 and a stator 14, which has a winding arrangement 16
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
The invention relates to a method for operating an electronically commuted motor (10), provided with a rotor (12), a stator (14) with a multi-thread winding arrangement (16), provided with an end stage (18) for electrical supply thereof, a first line (30) and a second line (32) for connecting the end stage (18) to a voltage supply (24) and a first regulator. The method comprises the following steps: a first signal (U_34; U_38) is recorded which characterises a current (I_N; I_N'; I_M; I_M') flowing through at least one of the lines (30; 32), depending on the first signal (U_34; U_38) a first value is determined, characterising the mean value of the current (I_N; I_N'; I_M; I_M') flowing through at least one of the lines (30; 32), a first adjustable value is determined in the first regulator, wherein the first regulator is provided the first value as actual value and a second value as set value, and at least one clock signal (PWM) is generated depending on the first adjustable value and supplied to the end stage (18) in order to influence the first value. The invention further relates to a corresponding motor (10).