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Calorimetry for power conversion in mobile telephone chargers
Abstract
This paper describes the measurement of power losses of two different types of charger for mobile telephones. The losses were measured during charging, at the end of charging and with the chargers powered but disconnected from their loads. Those losses were measured directly by a calorimeter with an accuracy of plusmn100 mW and by two variations on the method of subtracting output power from input power. The work shows that the losses of modern chargers are around 1 to 2 W when charging but under 200 mW when powered but disconnected from the telephone. The calorimetric method is shown to have advantages.
... Different types of calorimetric measurement principles are presented in the contributions [1] to [6] (see Figure 1-3). Closed type chambers have high requirements on the isolation of the case and fluid cooling system. ...
Power loss measurement of power electronic components and overall systems is sometimes difficult by use of electrical quantities and in few applications even not possible. The calorimetric power loss measurement is an established method to identify the overall system losses with a suitable accuracy. This paper presents a novel method with an open chamber calorimeter under accurate air mass flow, air pressure, humidity measurement and temperature control. The benefits are the approximately halved measurement time compared to established systems and the possibility to control the chamber temperature. So it is possible to measure the power losses at different ambient temperatures.
Because of losses in electricity conversion and storage only part of the energy taken from the power grid produces useful work in a battery-operated mobile device; the rest evaporates as heat. The authors analyze the recharging activity of a mobile phone to understand the efficiency of the different units involved (charger, EPM chipset, battery). Their measurements show that the efficiency is quite low; only about 15% of the electricity from the power grid ends up being used for the actual computing and communication elements of the mobile phone. It seems that there is room for improvement in the recharging efficiency. However, as the consumption of electricity of a single phone is small the incentive for improvements has been weak.
This paper studies the electricity consumption of mobile phone chargers. The charger's electricity consumption varies depending on its state. We measured the electricity consumption of various phone and charger models in different states. We also did panel studies on the recharging behavior of smartphone users. Based on these and other sources, we are able to estimate mobile phone recharging electricity consumption, cost, and CO2 emissions both in Europe and in the USA. Our analysis shows that the actual recharging of batteries consumes only 40% of the total energy; the rest is wasted mainly by unnecessarily plugged-in chargers consuming 55% of the total energy.
The direct measurement of losses in power electronic systems is possible through the use of a calorimeter. An improved and fully automated version of a double-jacketed closed-type calorimeter is described in this paper. The accuracy of the calorimeter has been confirmed by calibration tests and is better than 0.1 W in 25 W. The losses in mobile (cell phone) chargers and the ballasts of compact fluorescent lamps have been measured in this calorimeter and are compared to those obtained from conventional measurement methods.
Calorimetry allows direct, accurate measurements of losses in power electronics systems. A small-scale version of a double chamber, closed type calorimeter for measuring losses up to 20 W is described in this paper. The design comprises an inner chamber with heat exchangers integrated into the top and bottom of the chamber, surrounded by insulation. This is enclosed by a temperature controlled air gap, within a further insulated enclosure. Calibration tests show that losses can be measured to a precision of +/- 0.4 W and ways of improving the accuracy further are discussed
High precision calorimetry permits the direct measurement of losses in power electronic systems. This paper describes improvements to the design of a double- jacketed, closed type calorimeter in order to make these measurements. Calibration tests have confirmed that the new design can measure losses to an accuracy of better than 0.5 W in 200 W. This calorimeter has been used to verify the accuracy of models for inverters for use in variable speed drives for domestic appliances. Verification has been undertaken at a range of switching frequencies and confirms the ability of the models to predict inverter performance without recourse to physical prototypes.
Measuring power loss accurately is of great importance for power electronics systems design and for assessing system performance and reliability. This paper reviews various power loss measurement techniques in power electronics systems. A brief overview of electrical methods for loss measurements is given. Calorimetric methods, the most accurate of all instruments for measuring power loss, are described along with their implementations. The pros and cons of various techniques are discussed and compared for estimating the losses in integrated power electronic modules (REM).
In this paper. we report the use of a closed type calorimeter with
a secondary cooling circuit of water and direct measurement of power
losses. The target specification is the determination of losses up to
600 W to accuracy of 1 W or about 0.2% of full scale. A second thermally
insulating enclosure is used to prevent heat loss through the
calorimeter walls and enables accurate direct measurement of the power
to be made without increasing the time constant of the thermal system.
The calorimeter has been designed for motors up to a frame size of 90S,
or about 1.1 kW, which is suited to the measurement of machines for
domestic appliances. Initial results show that the calorimeter is
accurate to at least 2 W with a resolution of about 0.1 W
This paper discusses the calorimetric measuring system. The calorimetric principle is one of the most promising methods for accurate power measurements. A calorimetric wattmeter provides a useful tool for use in the developments of new, energy-efficient, electrical components for industrial and consumer products. Power measurements can be performed with an accuracy of 0.2% of full-scale deflection using the proposed calorimetric measuring method.
In this paper, coreless printed-circuit-board transformers are
characterized. A range of coreless printed circuit board (PCB)
transformers with different geometric parameters have been fabricated
and tested. Based on a recently reported analytic method, the self
inductance of these transformers is calculated. This analytical method
is also extended to cover the prediction of the transformers' mutual
inductance. All calculated parameters have been confirmed with
measurements for the frequency range from 100 kHz to 30 MHz. These
results provide useful information for the optimal design of coreless
PCB transformers
Measuring power loss accurately is of great importance for power electronics systems design and for assessing system performance and reliability. This paper reviews various power loss measurement techniques in power electronics systems. A brief overview of electrical methods for loss measurements is given. Calorimetric methods, which are considered the most accurate of this purpose, are described along with their implementations. The pros and cons of various techniques are discussed and compared for estimating the losses in integrated power electronic modules