In the art of electric motors and controllers thereof, an electronic circuit of the controller largely includes three functional modules; i.e., a control board, a power module (particularly, an intelligent power module, IPM) and a gate driver. Generally, according to usage of electric power, the controller can be sorted to a control-type controller or a power-type controller. The control-type controller uses a current with a small power for generating control signals. On the other hand, the power-type controller receives a foreign big power, such as a battery power. The received power is processed firstly, and then regulated by control signals from a control-type controller so as to provide a relevant big power for stator coils of an electric motor. As the big power flows in the stator coils for inducing an electromagnetic field to drive a rotor of the electric motor, so that a corresponding kinetic energy can be outputted. However, if the same mechanism as described above is reversed kinematically and electrically, a different function would be formulated. Namely, if the rotor of the electric motor is rotated by foreign forcing, the electric motor would react as a generator, by which the stator coils would generate a big power. Then, the power-type controller would receive this big power from the electric motor, process the big power according to control signals from the control-type controller, and then output the big power for further usage; for example, to charge a battery.
Recently, as the progress in electronic technology, a volume of controller is significantly reduced, and thus a corresponding power density is increased. Actually, such a development is good for mechatronics. Though the volume is reduced, yet the controller still needs to output a current with a big power to the electric motor. In other words, the output power of the controller is never reduced, no matter what the volume is. Nevertheless, heat generated upon running the controller is always a problem to the controller. Obviously, this heat shall be properly and quickly handled to dissipate or be removed off, or the controller would be in a jeopardy of burning down.
While in mechatronics, a move of mounting the controller to a shaft end of the electric motor will meet inevitably two difficult problems yet to be resolved.
One of these two problems is at the wiring of the stator coil of the electric motor. Specifically, while in wiring the stator coil, an arrangement of ends of electric wires does present typical difficulty. In practice, according to a phase number and a polar number of each the stator, different sets of wired coils would be provided to flow electricity so as to induce a corresponding electromagnetic field. Each of the coils has an in-flow end and an out-flow end; i.e., every coil presents two wire ends. These two wire ends shall be individually soldered, according to the wiring arrangement, to electrically couple a power-supply cable from the controller. By having a three-phase electric motor as an example, three coils are included, all wire ends of the coils would finally soldered to a ground port and three voltage ports, respectively, so as to form a specific type of stator coils, such as a Y-type wiring, a A-type wiring, and so on. Generally, each phase of the stator has at least one wire end. Soldering of this wire end shall be processed only after all the coils are assembled onto the stator (a set of silicon-steel plates) and after the stator is mounted into a stator shell of the electric motor. Namely, the assembling of all wire ends of the coils shall be performed in a limited space at one axial end of the stator inside the stator shell. Practically, this limited space is too narrow to make the assembling of the wire ends easy. Thus, the assembling quality is hard to be assured. In addition, after all the wire ends are soldered, the connection to the voltage port of the controller shall be processed. Since this connection is performed aside to the axial end of the stator shell, and if the controller is disposed close to the stator coils, then it will be difficult no matter what the connection is done by soldering or a mechanical means. Generally, a longer connection wire for connecting in between is required to establish the connection easier. However, an excessive length of the connection wire necessary to be completely squeezed into the aforesaid limited space will cause a higher impedance, and thereby a corresponding heat loss would be increased. Also, such a connection would make connection points vulnerable to break, and thus the entire quality of the electric motor would be reduced.
Another problem is also caused by the limited space, from which a reasonable arrangement for heat dissipation of the controller is hard to achieved; i.e., heat-dissipating of the controller would be hard to be satisfied. Nevertheless, it is always a problem in mechatronics to remove heat generated by a controller of an electric motor away from the limited space. In general, an air-cooling or water-cooling means can be applied to perform the heat dissipation thereof effectively. If the heat is not sufficiently dissipated, circuit components of the controller would be vulnerable to be burned down.
Namely, in order to increase the power density of a dynamic system, the output power shall be increased while the spatial occupation is kept the same or reduced simultaneously. For achieving a small spatial occupation in mechatronics, a resort of integrating the electric motor and the controller as a unique unit so as for reducing the entire volume becomes one of mainstream developments in the field of electric motors. However, in mechatronics, the reduction in the space for assembly would induce inevitably plenty shortcomings, such as design difficulty, assembly difficulty, heat-dissipation difficulty, assembly quality down, and so on. These shortcomings are issues needed to be encountered for R&D people all around the world in the industry of electric motors.
Accordingly, a development for a cooling structure integrated with an electric motor and a controller that can both resolve the aforesaid two problems in wiring arrangement and heat-dissipation of the controller, and provide advantages in simple structuring, easy assembling, well heat dissipating and quality construction is definitely urgent to the skill in the related art.