ScubaSteve
09-01-2004, 02:30 PM
Air gap - The smallest space from the front of a magnet and the stator tooth. Easily calculated using simple geometry. The smaller the air gap, the stronger the magnetic field, the lower the Kv, RPM, and current draw.
Flux - Magnetic flux is the product of the magnetic field times the projection of the coil area onto the plane perpendicular to the magnetic field. It's unit of measure is Gauss.
Io - No load current measured at full throttle with no propeller. This is the minimum amount of current required to spin the rotor.
Kt - This number is the motor torque constant expressed in inch-ounce of torque per amp of current. This number is the amount of torque a motor would produce per amp of current draw. As an example, the a motor with a Kt rating of 0.45 in-oz/amp drawing 5 amps would produce 2.25 in-oz of torque (5 x 0.45).
Kv - The motor constant that shows how fast a motor will turn at a given input voltage. Expressed as RPM/V. Measured with no load at WOT (wide open throttle). Knowing the input voltage (and neglecting internal resistance) a motor with a Kv of 1900 powered by 8V would ideally spin 8 * 1900 = 15,200 RPM.
Magnet - Refers to one physical magnet. Magnets are described by their dimensions (i.e., 5x5x2mm) and their rating (i.e., N45, N48, N50) with higher numbers meaning a stronger magnetic field. The stronger the field, the lower the Kv, the lower the amps, and the slower the rotor spins at a given voltage.
Magnet wire - Thin guage wire with a thin insulation coating used to wind motors. Beginner wire, or "newbie wire", has a thicker coating (also called "build") to reduce the possibility of shorts.
Magnetic circuit - Refers to the path of magnetic flux from the face of the permanent magnets, across the air gap, through the stator tooth, back through an opposite-polarity tooth (a neighboring tooth), back across the airgap, through the back iron, and back to the opposite face of our original magnet. As you can see, it's a complete circuit similar to an electrical one.
Pole - Refers to a magnetic pole (either north or south) and can be composed of one or more magnets. For example, it is quite common to use many smaller magnets of like polarity to make up a wider magnet pole. Notation in this instance is NN SS NN, which signifies two magnets are used for each pole.
Rotor - The rotating portion of a motor, and, in the case of outrunner motors, the outer-most element of the motor. A rotor must have a flux ring (also know as back iron), a shaft, and an even number of magnetic poles.
Short - Abbreviated term for short circuit . It usually refers to a point where the magnet wire in a winding is exposed and is either being rubbed or punctured. When this occurs, several turns are effictively removed from the winding and thus resistance goes down and current goes up. Typically the motor will run very poorly (if at all) and consume vast amounts of current, usually burning itself or the ESC up if not monitored.
Stator - The stationary portion of the motor. These are made up of thin steel laminations called a stack with insulation on top and bottom to protect the windings from sharp edges. Windings made up from magnet wire fill in the spaces between the teeth. Multiple stators can be stacked (i.e., double, triple, etc.) to increase power-handling capability.
Tooth - Also called a stator tooth, and sometimes incorrectly called a stator pole. It is the part of the stator that you wind your wire around. It usually has a hammerhead end to reduce stray flux.
Turn - A full loop of wire around a stator tooth. Also call a wind. Multiple turns are referred to as a winding. Express as T when describing a motor configuration (i.e., 15T 24AWG).
Winding - A groups of winds or turns of wire on a stator tooth. In a winding diagram, capital letters refer to clockwise turns and lowercase letters refer to counterclockwise turns.
(Thanks to JayC for his work compiling this information, and also to everyone who contributes to this growing resource!)
Flux - Magnetic flux is the product of the magnetic field times the projection of the coil area onto the plane perpendicular to the magnetic field. It's unit of measure is Gauss.
Io - No load current measured at full throttle with no propeller. This is the minimum amount of current required to spin the rotor.
Kt - This number is the motor torque constant expressed in inch-ounce of torque per amp of current. This number is the amount of torque a motor would produce per amp of current draw. As an example, the a motor with a Kt rating of 0.45 in-oz/amp drawing 5 amps would produce 2.25 in-oz of torque (5 x 0.45).
Kv - The motor constant that shows how fast a motor will turn at a given input voltage. Expressed as RPM/V. Measured with no load at WOT (wide open throttle). Knowing the input voltage (and neglecting internal resistance) a motor with a Kv of 1900 powered by 8V would ideally spin 8 * 1900 = 15,200 RPM.
Magnet - Refers to one physical magnet. Magnets are described by their dimensions (i.e., 5x5x2mm) and their rating (i.e., N45, N48, N50) with higher numbers meaning a stronger magnetic field. The stronger the field, the lower the Kv, the lower the amps, and the slower the rotor spins at a given voltage.
Magnet wire - Thin guage wire with a thin insulation coating used to wind motors. Beginner wire, or "newbie wire", has a thicker coating (also called "build") to reduce the possibility of shorts.
Magnetic circuit - Refers to the path of magnetic flux from the face of the permanent magnets, across the air gap, through the stator tooth, back through an opposite-polarity tooth (a neighboring tooth), back across the airgap, through the back iron, and back to the opposite face of our original magnet. As you can see, it's a complete circuit similar to an electrical one.
Pole - Refers to a magnetic pole (either north or south) and can be composed of one or more magnets. For example, it is quite common to use many smaller magnets of like polarity to make up a wider magnet pole. Notation in this instance is NN SS NN, which signifies two magnets are used for each pole.
Rotor - The rotating portion of a motor, and, in the case of outrunner motors, the outer-most element of the motor. A rotor must have a flux ring (also know as back iron), a shaft, and an even number of magnetic poles.
Short - Abbreviated term for short circuit . It usually refers to a point where the magnet wire in a winding is exposed and is either being rubbed or punctured. When this occurs, several turns are effictively removed from the winding and thus resistance goes down and current goes up. Typically the motor will run very poorly (if at all) and consume vast amounts of current, usually burning itself or the ESC up if not monitored.
Stator - The stationary portion of the motor. These are made up of thin steel laminations called a stack with insulation on top and bottom to protect the windings from sharp edges. Windings made up from magnet wire fill in the spaces between the teeth. Multiple stators can be stacked (i.e., double, triple, etc.) to increase power-handling capability.
Tooth - Also called a stator tooth, and sometimes incorrectly called a stator pole. It is the part of the stator that you wind your wire around. It usually has a hammerhead end to reduce stray flux.
Turn - A full loop of wire around a stator tooth. Also call a wind. Multiple turns are referred to as a winding. Express as T when describing a motor configuration (i.e., 15T 24AWG).
Winding - A groups of winds or turns of wire on a stator tooth. In a winding diagram, capital letters refer to clockwise turns and lowercase letters refer to counterclockwise turns.
(Thanks to JayC for his work compiling this information, and also to everyone who contributes to this growing resource!)