how does an ecm motor work

Full Answer

What controls the speed of an ECM motor?

In summary, the ECM control converts AC single-phase power to DC power and then pulses that DC voltage appropriately to the three-phase motor windings. An ECM can change the 60-Hz frequency that controls the speed of the motor.

Are ECM motors variable speed?

The term "Variable Speed" actually refers to the blower motor inside the furnace or air handler. It's an Electronically commutated motor, or (ECM). ECM's are DC motors that function using a built-in inverter and a magnet rotor, and as a result are able to achieve greater efficiency than most AC motors.

Is ECM a DC motor?

ECMs are a type of DC motor. They are also called DC fan motors, EEM fan motors, and variable speed fan motors. They function using a built-in inverter and a magnet rotor, and as a result, can achieve greater efficiency in air-flow systems than some kinds of AC motors.

Does an ECM motor use a capacitor?

The ECM is one way of saving on energy costs. One of the characteristics of the ECM is that they do not require adding an external run or start capacitor. But a run capacitor may still be needed for the compressor. From the compressor the Start (S) and Run (R) leads are connected to the capacitor.

Do ECM motors need starters?

Overloads are no longer needed, as the ECM's internal rectifier converts the AC current to DC voltage at the motor. A motor starter is not necessary due to the built-in motor protection, but if the control features of the starter are desired, then one can be supplied.

How is an ECM motor controlled?

In an ECM, this process is controlled electronically by a microprocessor and electronic controls, which provide the ability to increase or decrease the speed of the motor. The type of ECM currently used by most residential HVAC systems is a brushless dc three-phase motor with a permanent magnet rotor.

How large can an ECM motor be?

Most ECM fans are limited to a maximum of 5 inch w.c. of external static pressure. Therefore, ECM is not suited for large applications that require high external static pressures.

Do EC motors require a VFD?

No. Because EC motor electronics convert incoming 50 or 60 Hz AC power to a DC voltage within the motor, the speed of the motor will be the same with 50 or 60 Hz AC power input (except in the case of ECR 82/92 motors, which are “mains synchronous”).

Are ECM motors direct drive?

ECM (electronic commutated motor) is a brushless DC motor with a permanent magnet rotor and a built in inverter. DC motors are more efficient than AC motors. They are also more expensive.

Do ECM engines last longer?

High efficiency will allow further energy savings. ECM motors are also quieter than traditional inefficient motors, have longer design life, and require less maintenance.

Are ECM motors reliable?

When applied properly, Electronically Commutated Motors (ECMs) are very reliable and offer long life. However, just like Permanent Split Capacitor (PSC) induction motors, when applied to an application that they are not designed for, their life cycle will be shortened.

How much energy does an ECM motor use?

At lower speeds ECMs can save over 60% of the electricity used by PSC motors. For example, in low speed circulation a typical PSC furnace motor will use 350 to 500 Watts while an ECM will use 75 - 125 W.

How does an ECM motor vary speed?

0:421:30Whats the difference between Variable Speed And ECM MotorsYouTubeStart of suggested clipEnd of suggested clipMost ecm motors are actually just four speed. Still where they just you set it and that's the amountMoreMost ecm motors are actually just four speed. Still where they just you set it and that's the amount of airflow you're getting whereas a variable speed it moves up and down.

What is the difference between a PSC and ECM motor?

The big difference between the two models is that the PSC motor has one speed: full speed. Any time that the blower is on it blows at full force. The ECM model is a variable speed unit that will adjust the airflow to optimal levels based on the desired temperature of the home.

What is a multi-speed ECM blower motor?

Rather than operating on the all-or-nothing principle, multi-speed blowers run at different velocities according to the temperature requirements of your home. They power up at full throttle and switch to a lower speed to maintain the desired temperature.

What is the difference between 2 stage and variable speed?

Two stage compressors don't turn on and off nearly as much. They're more efficient than single stage units, but not as efficient as variable speed compressors. Variable speed air conditioners run continuously, effectively dehumidifying the air inside your home.

What Is an ECM Motor?

ECM stands for "Electronically Commutated Motors," which basically means a motor that uses electronic control to change its speeds. There are three...

Use of ECM Motor:

The use of ECM motors is increasing rapidly. Today, all motors used in residential & light commercial HVAC (indoor and outdoor) and commercial refr...

How Does an ECM Motor Work?

Once the settings are programmed into the microprocessor at the factory and the control board dip switches are set to field, motor torque and airfl...

Advantages of ECM Motor:

An ECM motor consumes fewer wattages than normal motors. The multi-speed of the ECM motor allows it to reduce the drying effect that can occur duri...

Is Ecm Motor Disadvantageous?

The structure of an ECM motor is structurally complex as its stator has multiple windings & involves precise timing from some controls module to ro...

What is an ECM Motor?

The general consensus was that although we were familiar with the concept behind them – they are motors that regulate their own speed without the help of an external VFD or other device – none of us really understood the magic behind what makes an ECM Motor actually work. Without a VFD or external sensors to monitor pressure, temperature, or anything else, how the heck does the motor know when to speed up and when to slow down?

What is constant torque ECM?

A Constant Torque ECM is made up of two parts, the motor and ECM Microprocessor, that are both housed in one shell. The microprocessor is the “brains” of the motor. It holds the logic that controls the motor. The logic is a math equation or algorithm that figures out the ideal airflow for each specific piece of HVAC equipment out there and uses a formula to maintain that airflow using a calculation of the precise relationship between motor speed and torque.

What happens when a coil gets wet?

When the coil gets wet, the static pressure of the system goes up. As the static goes up, the motor senses a change in torque (like the car going uphill) and starts to increase the RPM of the motor in order to maintain the CFM of the system.

How does energy saver work?

The energy savings come into play when demand and static pressure decreases. When it is not needed at full speed, the motor can slow down, which uses far less energy. A motor running at full speed uses nearly 8 times the energy of a motor running at half speed.

Why does a fan need more torque?

Higher pressure essentially creates additional resistance on the blades of the fan motor, which is why it needs more “muscle” or torque to turn the motor. When the microprocessor senses increased torque, it automatically increases the speed of the motor.

Can ECM motors be programmed?

It should be noted that the ECM motor programming is specific to each model of HVAC equipment, so programming is ONLY done at the factory, not in the field. When ordering a replacement ECM motor, techs must know the specs of the model in which the motor will be installed for it to work properly.

What is an ECM motor?

ECM stands for “Electronically Commutated Motors,” which basically means a motor that uses electronic control to change its speeds. There are three types of ECM motor: constant CFM, constants RPM, & constants torque.

What are the drawbacks of ECM motors?

The most important feature of an ECM motor is its low energy consumption. The biggest drawback of this motor is its complexity. These motors are more prone to failure due to the electronics used in these motors. Let’s continue reading how ECM motors work, where it is used, and summarize the pros and cons.

Why does a fan need more torque?

An increased torque basically means that more “muscle” is needed to turn the motor. The higher pressure essentials create additional resistance on the blades of the fan motor, which is why it needs more “muscle” or torques to turn the motor .

Where is ECM programming done?

It should be noted that ECM motors programming is specifics to each model of HVAC type of equipment, so programming is only done at the factories, not in the fields. When ordering a replacement ECM motor, the tech must know the specifications of the model in which the motor will be installed to function properly.

Is CFM the same as RPM?

Since CFM, RPM and torques are all related, the basic principles are the same. But for the sake of eases of discussions, I am going to focus on the Constant Torque ECM Motor.

Does airflow reduce torque?

More airflow also lowers the static pressure, which reduces torque. At the same time, the increased airflow also provides the additional oomph of airflow that is needed to provide additional cooling or heating capacity to the system during times of high demand for the system.

Is ECM Motor Disadvantageous?

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What is the ECM in an engine?

In engines that have variable valve timing, the ECM is responsible for controlling the point in the engine cycle during which the valves open. Usually, the valves are opened sooner at higher speeds compared to lower speeds.

How Does An ECM Work?

The ECM interprets the information from the sensors using performance maps and adjusts the actuators accordingly.

What is the role of crankshaft position sensors in engine timing?

The crankshaft position sensors, which plays a vital role in the engine timing functions for spark events, valve timing, and fuel injection, monitors the engine RPM. The crankshaft position transmits data to the ECM, which then controls ...

What is the job of ECM?

It’s the ECM’s job to ensure the right amount of fuel is being injected. It does so by collecting and processing readings from various sensors. For instance, the oxygen sensors tell the ECM whether the engine is running lean (too much oxygen/too little fuel) or running rich (too much fuel/too little oxygen) compared to optimal conditions ...

Why is my ECM faulty?

Due to exposure to the elements , an ECM can become faulty over time. Moisture and corrosion damage are two of the most common culprits behind failing ECMs.

How does the coolant temperature sensor work?

The coolant temperature sensor measures how warm the engine is . If it’s too cool, the ECM sends the signal for additional fuel to be injected.

What is an ECM motor?

ECM motors, also known as variable speed motors, are motors that can vary the RPM of their motors. However, variation in speeds only happens when conditions within the system change. In the case of A/Cs and furnaces, the changes occur in an effort to maintain a programmed CFM.

Why use ECM motors?

Moreover, the ECM motor uses less wattage than the traditional PSC motor, further increasing the energy efficiency of the system. You can now appreciate why the ECM motors are fast becoming the industry standard for comprehensive energy efficiency.

What is the purpose of ECM motors in furnaces?

Behind today’s high-efficiency furnaces and A/C are higher efficiency motors designed to reduce the total electrical consumption, thereby raising the overall consumption of the system. This equipment also maintains the proper cubic feet per minute, better known as CFM across the various parts of the system, including the condenser coil, the heat exchangers, and the evaporator coils. Airflow is critical for these devices to operate properly. As such, the use of ECM motor technology helps in both these fronts.

Why does the AC motor increase RPM?

As the AC runs, the evaporator will naturally get wet, which causes the static pressure to go up. And as the static pressure goes up, the motor will sense some changes in torque. This can be equated to a car going uphill. As such, the motor will start to increase the RPM in order to maintain the ideal CFM expected of the system.

How does cruise control work when you go down a hill?

When you get to a hill, the cruise control will sense a change in torque and will rev up to maintain the predefined speed. The same case applies when you travel down a hill. The motor senses less torque and therefore, reduces the RPMs to maintain the predefined speed. This is the same principles that the ECM motor uses.

How many CFM does an AC motor need?

Let’s think of a hypothetical AC – 3 ton AC. For the AC to function correctly, we need a total of 1200 CFM or 400 CFM per ton. You program the board appropriately and both the adjust and cool profiles to as close to 1200 CFM as you can. Note that you should always use tables provided by the manufactures when you want to set up the ECM motor.

How many volts does a motor have?

These motors can operate with 220 volts as well as 110 volts, depending on the five pin power plug configuration. This system rarely breaks down and features exceptional reliability.

How does an ECM work?

Starting at the left side of the flowchart, on a call for heating or cooling, the thermostat closes and completes the circuit to the circuit board in an HVAC system . In most cases, the t’stat is the switch that closes and provides a path for 24 volts to the circuit board. The circuit board is programmed to operate the ECM at a specific CFM or at full speed. Many circuit boards can be set to start the ECM at a low speed and slowly ramp up to the programmed speed over a period of 5 to 8 minutes. The motor will slow down and stop when the thermostat is satisfied, and the fan switch is set to the automatic position.

What is an ECM control?

In summary, the ECM control converts AC single-phase power to DC power and then pulses that DC voltage appropriately to the three-phase motor windings.

What is an electronically commutated motor?

An electronically commutated motor is a three-phase, brushless DC motor. It comprises three major components: a circuit board, an electronic control module, and a three-phase motor with a permanent magnet rotor, as shown in Figure 1. The module and motor make up the actual ECM. The circuit board is used to set up cooling and heating applications.

What is the control module in Figure 4?

The control module in Figure 4 converts 120-or 240-V single-phase power to essentially three-phase DC power to operate the motor. The control module is a power inverter, which means it converts AC to DC. As shown in Figure 5, the motor appears as if it were a regular motor. The additional length is the electronic module that converts the single-phase alternating current to three-phase direct current power. Figure 6 shows the module and motor connected to the high-and low-voltage wiring.

What are the components of an ECM?

Basic components of an ECM. At left is the control module, in the middle is the three-phase stator, and on the right is the rotor, which is pulled out of the motor. Not shown is the circuit board. Image courtesy of RSES

What is the upper connector on a module?

Figure 6. The module section has two connectors. The upper connector is the high-voltage source. The lower connector is the low-voltage control source. The gray section in the upper part of the picture is the motor. The circuit board is not shown but will be connected to the other end of the two connectors. Image courtesy of RSES

What is an ECM in a car?

The ECM is basically an on-board computer in your car -- it's composed of hardware (a pretty standard circuit board) that's encoded with software (a program that tells the car how to run). See more pictures of computer hardware . Of all the things that can go wrong with a car, electrical system flaws are some of the most maddening.

What does ECM do?

It constantly monitors a vast network of sensors around the car to ensure conditions are within normal operating range. When something goes wrong, the ECM adjusts conditions or, if it can't, the car won't run properly or at all.

What is the purpose of ECM start up?

Part of the ECM's start-up procedure is to calibrate the position of the throttle at idle -- in other words, remind itself, and the throttle, how the engine should run when it's not being given any gas. This helps control and prevent an uneven idle.

What is engine control module?

The engine control module basically controls the intersection of the engine 's necessary ingredients to make energy -- fuel, air and spark. That sounds simple, kind of in the same way an engine itself sounds simple if you break it down into really basic terms. But the ECM accomplishes its considerable chore by constantly monitoring a vast network of sensors around the car to ensure conditions are within normal operating range. When something goes wrong, the ECM adjusts conditions or, if it can't, the car won't run properly or at all. When there's a problem, the ECM stores a trouble code so it can be diagnosed by a mechanic (with a scanner specifically designed for that purpose) and triggers the check engine light so the driver knows something's wrong.

How much does it cost to replace an ECM?

Replacement can cost anywhere from several hundred to several thousand dollars, and can be made more complicated (and expensive) if the ECM has to be modified to accommodate security systems, smart keys, immobilizers, or anything else electronic that is specifically configured to your car.

How to repair an ECM?

Actually repairing an ECM requires disassembling the unit and performing some pretty detailed, precision-critical electronics work. It's similar to repairing the motherboard in a desktop computer -- assuming it can be repaired it all. Some experts recommend removing and opening the unit, and sniffing around for the telltale signs of electrical damage (if you've never smelled it before, consider yourself lucky -- but you'll probably still be able to identify the chemical tang of burned metal). Also, if there is any corrosion from acid or moisture damage, it'll probably be easily visible. If you're not planning to do the repairs yourself, the only benefit to this step is that you'll know you're on the right track with your diagnosis. That said, the absence of such evidence does not mean the ECM is fine. Got that?

What happens when your foot touches the gas pedal?

Previously, when your foot made contact with the gas pedal, it was connected to a cable that went directly to the engine so the engine could decide how much fuel to inject, based on whether you caressed the pedal, mashed it to the floor, or most likely, somewhere in between.

How does an ECM work?

An electronically commutated motor (ECM) uses a microprocessor controller that sequentially energizes/de-energizes each winding of the stator with power to generate an electrical current. Like the other types, this processor-based pulse control builds the magnetic field that causes the rotor inside this ring of magnets to turn; but unlike the others, the microprocessor is using a closed loop feedback mechanism to more precisely control the magnetic fields as to minimize the eddy currents and losses used by traditional mechanically commutated motors. This allows a brushless motor to be able to be used, thus reducing points of physical contact within the moving components of the motor.

Why are EC motors important?

EC motors are very valuable for small motor sizes, where a variable frequency drive (VFD) is not cost-effective . They are also great for installations where constant design flow is required because the motor design is more efficient. For larger motors where the parameters fluctuate (such as VAV or VRF systems), a VFD can vary the motor speed to match the variable load. In these applications, the efficiencies of the inner workings of the motor are the driving force behind the energy savings.

How does a PSC motor work?

Permanent split capacitor (PSC) motors use a capacitor in one of the windings to increase the current lag between the two windings to make the rotor turn. Often one winding is called the start winding and a run winding. These two windings are used in conjunction with a capacitor to help provide more starting torque and it also helps correct the power factor of the motor. In both technologies, there are varying degrees if inefficiencies because of the way the fields are created/controlled through their coils. Also, there is a physical counter force created by fields on their own coils! These are due to eddy current s (or circular currents of magnetic force) and they increase the inefficiency in the motors.

What are the two sets of wires that surround the stator and the rotor?

These are called the windings. The windings in the stator are stationary and the magnetic field they generate exerts mechanical force on the opposing field in the rotor windings thus causing ...

Why are there two windings in a motor?

These two windings are used in conjunction with a capacitor to help provide more starting torque and it also helps correct the power factor of the motor. In both technologies, there are varying degrees if inefficiencies because of the way the fields are created/controlled through their coils.

What type of motor is used in HVAC?

There are many different types of electric motors and configurations, but there are three types used mainly in HVAC and refrigeration applications: shaded pole (induction), permanent split capacitors (brushed DC), and electronically commutated motors.

What is mechanical commutation?

Traditionally these motors use a form of mechanical commutation (the moving part of the motor that switches current through the windings). You can almost think of this as the timing component of the motor. This mechanical commutation introduces additional inefficiencies depending on the type of commutator (or electronic switch).

When was the variable speed ECM introduced?

Theconstant-airflow(variable-speed) ECM was introduced in 1987 by GE (rebranded Genteq™ in 2009). It was the first and only indoor blower ECM until the introduction of the constant-torque ECM in 2006. The term “variable-speed motor” was coined in the late 1980s. By function it is a “constant-airflow motor.”. Both of these terms define the type ...

How to check if a motor is good?

Winding test. Ohm out the motor windings from each terminal in the connector to ground, using the endshield or unpainted brace as ground. Set your ohmmeter to the highest scale (no megohmmeters). If all of the readings are above 100,000 Ω, the motor is good (assuming it also passed the previous test). Typically a good motor will show all readings as infinity, which, depending on the meter, will display on the digital readout as “I,” “OL,” “Open,” or the symbol ∞(see Figure 12). If any of the readings is below 100,000 Ω, the motor has failed and must be replaced.

What is constant airflow?

Constant airflowis the ability of the variable-speed motor to maintain its programmed and field-selected airflow per demand, even when the total ESP is higher than recommended and/or changes during system operation. The total ESP (the resistance to the movement of air) is increased when ductwork is undersized, poorly constructed, and/or full of dirt or debris. The total ESP can increase during system operation when dirt builds up on the air distribution system components (especially the filter), and when customers close or block grilles and registers. The variable-speed motor is programmed to maintain airflow during all of these situations, within the limits of the OEM programming and motor design. By contrast, torque (current) and airflow will decrease when the total ESP increases in PSC induction motor systems (see Figure 3). When set up correctly, the benefits of the variable- speed motor system include: energy savings improved outlet air temperature for each system demand improved humidity control improved system capacity reduced space temperature swings reduced air noise with soft start/stop and gradual changes between airflow demands, delays, and/or profiles reduced constant fan air noise with low cfm settings, plus increased energy savings over normal system operation reduced repairs associated with continuous low- airflow operation.

How to determine if a power choke is good or bad?

To ohm out this device, turn off the power to the system and disconnect the wires at the choke. Evaluate the choke as follows: Measure the resistance across the choke: Good choke = low resistance (typically less than 1 Ω) Bad choke = open or 0 Ω Bad choke = resistance above 2 Ω Measure the resistance from either terminal to ground : Good choke = infinite resistance (open circuit) Bad choke = any resistance below 100,000 Ω (100 kΩ)

What are the advantages of a 4- HP motor?

This chapter covers only the current-generation motors. The three main benefits of these motors over conventional induction (PSC) motors are: increased electrical efficiency more precise and unlimited airflow selection (the “variable-speed” feature)

How to connect a TECMATE PRO to a power supply?

OFFposition. The TECMate PRO has two wires with alligator clips for connecting to a 24-V ac power supply (they are not polarity-sensitive). The green LED on the TECMate PRO will light up when the device is properly connected to the 24-V ac power supply. The 16-pin connector from the TECMate PRO is connected to the motor in place of the OEM 16-pin harness or 4-pin harness with the provided adapter (see Figure 9). The 5-pin high-voltage connector must be connected to the motor with its power confirmed and the system power turned on (after all of these connections are completed) for this test. If the motor runs when the TECMate PRO switch is turned on, the problem is not the motor—the problem is before the motor in the HVAC system. If the motor does notrun with the TECMate PRO, then the motor control has failed and will need to be replaced. The motor itself, however, may still be good.

What is variable speed motor?

Both of these terms define the type or style of ECM and how it is programmed to function. Variable-speed motors are built in 1⁄. 3-, 1⁄. 2-, 3⁄.

Function

Controlling The Air-Fuel Ratio

Controlling Idle Speed

Control of Variable Valve Timing

• In engines that have variable valve timing, the ECM is responsible for controlling the point in the engine cycle during which the valves open. Usually, the valves are opened sooner at higher speeds compared to lower speeds. This can increase the amount of air flowing into the cylinder, increasing fuel economy and boosting power.

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What Causes An ECM to Go Bad