Basic Information about Speed Controllers Controllers of the MGM compro company are manufactured in two basic series. The first one is called SMM (Standard Motor Management) and is represented by small processor controllers made especially for slow and park flyers and aircrafts. The second series called TMMŪ and TMMŪ extra (Top Motor Management), have outstanding and unique features thanks to the Hi tech TMMŪ technology of the MGM compro company. These controllers are meant for aircrafts, gliders, helicopters, race boats, cars, ships and submarines. Controllers of either of these two series are suitable for all kinds of DC (direct-current) electro motors as long as the maximum working currents and the number of cells are respected. (e.g. Speed, Model motors, Potensky, Mega, Mabuchi, Trinity, Corally,
) Controllers marked "3ph" are designed for brushless sensorless electro motors such as e.g. Mega AC, Model motors, MP JET, Kontronik, Plettenberg, LRK, Hacker and others. Maximal practical value and safety of operation of both, the controller itself (throttle will not turn without proper signal from transmitter, it is not possible to start from differ-ent position than "minimal throttle" position) and the BEC which plays an important part in safety of operation of models was taken into consideration while designing the controller. TMM Controllers for Models TMMŪ controllers are high-end crystal controlled programmable or automatically programmed controllers made predominantly with the use of surface mounting. They ensure absolute constancy of set and programmed parameters and values (applies to programmable types). All parameters are purely program set (or are automatically set) without any mechanical elements (trimmers etc.) and this setup remains constantly retained until further possible change of parameters. As they use newest efficient processors (single-chip micro mini) for their operation they are able to automatically find some of these data and values (APS). Others may easily be modified due to user programming, thus changing some of the controller properties to meet particular needs. At the same time, due to the controller "hardware" and "software" capabilities, the whole series of protective and optimizing processes have been used. These processes considerably reduce the possibility of unmeant damage to both the motor and accumulators and, of course, the controller itself.
The motor is perfectly protected from damage caused by excessive current at crisis points (e.g. locking the motor under full load) by the automatic current fuse (ACF). In case of exceeding automatically set current limits the motor according to the nature and intensity of the overload becomes switched off either immediately or 1 or 2 or more sec later. In all present versions the operation is resumed after dropping the throttle to zero after current fuse switch off.
Accumulators are protected in three ways. Firstly, due to the use of ACF the current overload of accumulators (and possible damage) at crisis points can be avoided. Secondly, the used system of intelligent power reduce (IPR) ensures through measurements of number of cells, voltage, currents, accumulator condition and calculations always an optimal point of starting continuous reduction of motor performance (it starts to be efficient when accumulator becomes heavily discharged) so that accumulator cells do not get extremely discharged which reduces the possibility of reversal of poles of lower cells. This at the same time enables retaining defined energy for BEC (perfect RPC) which is of great significance e.g. for gliders, helicopters etc. (a crash due to running out of energy for receiver can be avoided) and ships (see "Unique properties of TMMŪ - more information"). Thirdly, it is the automatic current reduce (ACR) due to which a drop in voltage for BEC under extremely big current load (for every given controller) while motor starts does not occur.
Controllers work with high switching frequency of the motor (PWM 2, 4, 8 kHz), which is an advantage. The current ripple is reduced, possible interference is lessened, BLDC motor commutator is not wear out so much (it's service life is longer) and also the efficiency is higher. Some of TMM controllers use the "synchronous rectification" system: the clamping schottky diode is replaced by suitably controlled FET transistor. Among the benefits of this system is a significant reduction of power loss of the controller and significant reduction of warming up as well as increased efficiency.
The controllers efficiently mask interference and dropouts up to 0.7 sec (respectively up to 1.5 sec.). When there occur long lasting dropouts the controller slowly reduces motor revolutions to full stop. Without the proper signal from the transmitter (e.g. transmitter is turned off), the motor neither jerks nor runs but is at standstill. Motor will not start running before the throttle stick is in its minimal position.
Thermal fuse of the controller is set to 90°C or 150°C when performance is reduced to ca 60% or motor revolutions are very slowly reduced to zero. After switching on, the temperature above 70°C is monitored; if the temperature is higher the controller does not start.
Some of the types may generate signal informing that there is a danger of accumulators getting discharged quite soon etc, using extremely bright LED or using acoustic piezzo buzzer. Controllers are turned on by turning off the switch. Possible damage to the switch has no negative effect on the controller operation and BEC - both remain fully operational.
All operating conditions are indicated by LED diodes or by motor beeping (important primarily in case something does not operate according to your criteria, and also when programming). Also more powerful types of controllers in combination with less powerful motors can be operated without any problems, all protective mechanisms being preserved. Some types are also made as the so-called "hydro" versions ensuring the controllers resistance to water. Due to their design (compact assembly on the printed circuit card with recessed SMD micro devices is encased in an aluminum protective box or in heat shrinking sleeve) they feature a high degree of robustness. The controllers of the range TMM in standard versions come with the JR connector on servo cable 0.15mm2 or 0.25mm2, but without connectors on power cables. NiCd, NiMH and Li-Ion, Li-Pol accumulators are suitable for use as feeding accumulators, unless it is recommended differently for a concrete type.
These controllers may be used for controlling electro motors in models, any other applications or loads (resistor, bulb, etc.) are not allowed. Controllers may be fed only from accumulators. The "continuous current" information in the table applies to cooling controllers. Control signals are positive pulses 1.5 ms ą 0.8ms with period 10 up to 30 ms. Basic Advantages of TMM controllers shown in graphs: 
The controller's behavior at the point of exhausted batteries (or closely before that) is very significant from both the controlling point of view and economical use of remaining energy point of view.
When switching (reducing power) the motor off at solid boundary there is only very little energy remaining for BEC. The better accumulators are used the less energy (time) is left to land (standard accumulators). Comparing to this, TMM ensures the remaining energy to be big enough; it is also possible to modify its size in some types (greater for gliders). This energy is certainly insignificant as long as duration of running the motor is concerned, but it is very significant for feeding BEC. The reduction of motor revolutions starts at the point when the motor power would be decreasing fast due to rapidly falling feeding voltage. Motor would draw the remaining energy from batteries very fast . This energy is therefore rather preserved for BEC (that means for servos and receiver) for which is big enough. Simultaneously, the possibility of reversal of poles of weaker cells is reduced. 
In case the current of the motor when overloaded does not exceed the limit of the current fuse of the controller, the fuse does not switch off and the motor is very likely to burn down or to be seriously damaged (standard controllers). When using TMM the motor (possibly also accumulator) is saved due to ACF. |
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