MX2011005062A - Power saving system for evaporative air conditioner. - Google Patents

Abstract

The present invention discloses a plurality of modules useful for controlling the electric power consumed by an evaporative air conditioning system, with the aim to save consumption of electric power used for conditioning the temperature in residential houses by replacing a split-phase, single-phase induction motor by a three-phase induction motor powered by a space vector voltage inverter. The main modules of the present invention are: a single-phase rectifier, in charge of maintaining the DC voltage at a level required for the three-phase voltage inverter to operate, this rectifier being also responsible for a soft start in order to avoid current spikes which may abrade the system components. - a controller which maintains the power flowing to the motor by using the modulation Space Vector technique (SVPWM), thereby using the DC voltage efficiently and allowing a waveform with low harmonic distortion to be synthesized, with the goal of supporting the highest possible efficiency. - a voltage inverter with pulse width modulation based on Space vectors (SVPWM) which, when compared with other modulation techniques, allows a better use of the voltage generated by a semi-controlled rectifier. By using a passive LC low pass filter, the high frequency harmonics generated by the high switching frequency are eliminated.

Description

Energy saving system for evaporative type air coolers DESCRIPTION OBJECT OF THE INVENTION The invention aims to provide an alternative energy saving system for evaporative air apparatuses with variable speed control of wide range for this type of apparatus, which means an improvement over traditional systems that only have 2 speeds and that also allows us to reduce the electric energy consumption of evaporative-type air coolers for residential use.

BACKGROUND The evaporative air coolers are used in warm or semi-desert areas where there is a type of dry climate, and through the humidification of air that enters the equipment allows creating a comfort zone inside homes, commercial or industrial premises. The air coolers used in the home use split phase single-phase induction motors, which require starter auxiliary windings and which, due to the nature of their design, have a low efficiency.

By using a three-phase motor and a vector space converter, efficiency can be increased by 28%, which represents a saving in energy consumption. In order to exemplify the energy saving, if we consider a city with 50,000 houses, of which 80% have a washing machine that uses a mon HP single-phase motor, it would have an energy saving of 13,055 kWh. . The above considering that the engine is running at 100% of its rated load. When a motor driven by a voltage inverter is used, greater efficiencies can be achieved, since the evaporative type air cooler will only be used to create the necessary comfort in a house, that is, there are commonly times when it can be done. have a comfortable environment with a reduced speed and thereby reduce the electrical energy consumed by the electric motor.

BRIEF DESCRIPTION OF THE FIGURES Figure 1 shows the complete system, it shows the rectifier that feeds the inverter, the control device and the driver circuit of the inverter are shown, which together are responsible for the operation of the electric machine that drives the air device . Figure 2 shows a schematic diagram, where in a DSC (digital signal controller) is responsible for generating the trigger pulses that are sent to a set of six IGBTs that are responsible for generating three-phase voltage signals and variable frequency that will feed the induction motor.

Figure 3 shows the door driver circuit (Driver) that is responsible for conditioning the DSC trips for the correct operation of the voltage inverter IGBTS, Figure 4 shows that the voltage signal of the electrical network is rectified by a single-phase rectifier, this rectifier is controlled by the DSC by means of a DAC that generates the control voltage of same and the output voltage of this rectifier feeds the three-phase bridge of IGBTs.

Figure 5 shows the electronic card that contains the DSC and the door driver responsible for operating the voltage inverter contained in the system.

Figure 6 shows the card containing the rectifier circuit control that provides the DC voltage required by the inverter.

Figure 7 shows the waveform synthesized by the voltage inverter with which the three-phase induction motor contained in the air conditioner is fed.

DETAILED DESCRIPTION OF THE INVENTION The invention consists of an energy saving system for evaporative air conditioners or commonly called washed air, the schematic of the invention is shown in Figure 1. The energy of the system is supplied by the distribution network of Federal Commission of Electricity (CFE) (1), this is fed to a voltage rectifier (2) and later to a three-phase inverter based on vector spaces (3), which has the function of driving a three-phase induction motor (4) that is in the air device conditioned. This inverter is operated by a door driver circuit and a digital signal contrr (DSC) preferably dspic30f3011 (Figures 2 and 3). This contrr receives the command of the speed desired by the user through a potentiometer (5) and generates the sequence of shots based on vector spaces necessary to create the three-phase voltage signal, and variable frequency necessary to drive the three-phase induction motor , which are tasks that require intense computing power in real time. It is important to mention that the DSC is also responsible for the control of the rectifier circuit, thus having an effective control over the DC voltage that is used to power the three-phase voltage inverter.

The above allows to vary the speed of the engine in a wide range of speeds instead of having only 2 predefined speeds, helping to save energy. The shots generated by the DSC are transmitted to the driver by means of opto couplers preferably 6N137 (6), in this way the user is electrically isolated from the network effectively, the pulses are subsequently fed to the IR2130 IC (7) that drives the IGBTs of the three-phase voltage inverter, to power the electric motor. This circuit has different characteristics such as protections due to voltage drops and current peaks that protect the motor and the system from any electrical failure, thus effectively avoiding damage to it.

The single-phase voltage rectifier (Fig. 4) is controlled by the DSC via SPI, this communications protocol is used to modify the control voltage by means of a Digital to Analog Converter (DAC) (8), this control voltage is used to determine the firing angle of the thyristors, that way the output voltage of the rectifier is effectively adjusted. The rectifier has an analog synchronization system (9) that keeps the shots in phase with the CFE voltage (1), this phase is used in conjunction with the command signal to determine the activation of the thyristors according to the desired voltage. This signal is later multiplied by the oscillations of an astable timer (10), this is added for the purpose of transmitting the shots to the doors of the thyristors by means of isolation transformers (11), in such a way that it remains electrically isolated. any circuit that can be manipulated by the user. The presence of this rectifier allows the system to have a soft start that avoids the peaks of currents associated with the load of the capacitor and the start of the motor, effectively increasing the life time of both the installation and the components of the system to be subject to Less stress at startup. It is also important to mention that the presence of the rectifier allows to regulate the DC voltage before variations of the line by CFE.

Additionally, it is important to mention that the efficiency of a three-phase induction motor is higher than that of a single-phase motor, so even with a maximum speed of rotation in the motor, there will be a saving of 28% in the energy consumed. In this way, it is possible to have a three-phase signal from a single-phase installation in an effective way. It is also important to mention that the presence of the DSC allows to include temperature and humidity controls for the system control.

Claims (3)

CLAIMS Having sufficiently described my invention, I consider it a novelty and therefore claim as my exclusive property, what is contained in the following clauses:

1. Energy saving system for air coolers of the evaporative type, characterized in that it is comprised of; a voltage rectifier that feeds a three-phase inverter based on vector spaces which is operated by the use of a three-phase voltage inverter based on vector space modulation (SVPWM), this inverter is operated by a gate driver circuit and a controller digital signal (DSC) preferably dspic30f3011, this controller generates the sequence of shots based on vector spaces necessary to create the three-phase signal of variable voltage and frequency necessary to drive the three-phase induction motor.

2. Energy saving system for evaporative type air coolers, according to claim # 1, characterized in that it has a door driver circuit, which is preferably composed of an IR2130 IC and opto couplers 6nl37, this device electrically isolates to the user of the voltage of the electrical distribution network and conditions the shots for the IGBT's doors, additionally it is in charge of the insertion of the necessary dead times in the switching and has protection against voltage drops and over current.

3. Energy saving system for evaporative type air coolers, in accordance with claim # 1, characterized in that it has a rectifier circuit, which avoids the presence of current peaks during startup and helps regulate the DC voltage necessary for the operation of the investor. Energy saving system for evaporative type air coolers, according to claim # 1, characterized in that it has a control module, which generates the sequence of shots to carry out the SVPWM modulation used to drive the motor of three-phase voltage induction, this module is also responsible for the controlled rectifier control that provides power to the voltage inverter and gives the user the ability to operate the air device over a wide range of speeds instead of only 2 predetermined speeds.