quality DC Brushed Motor & Magnet DC Motor factory

Electric motors are widely used in several electronic applications, to the point that we can say they are everywhere. In our homes we have multiple examples, such as fans, hair dryers, fan heaters, kitchen appliances and more. If we then consider a car, we can soon discover that there are different types of electric motors inside a vehicle: heating system, radiator cooling fans, electric windows, electric mirrors, seat control and much more. This article, based on the eBook from the “For dummies” series published by Qorvo [1], will introduce the fundamental concepts that every designer, maker, or student must master to face a motor control application. Brushed vs brushless motors There are different types of motors on the market, which the designer must select based on the technical and economic requirements of the specific application. The main categories of motors are the following: brushed, brushless (in turn divided into BLDC and PMSM), induction, and stepper. Figure 1 shows the four types of electric motors mentioned above, with a summary of the main advantages and disadvantages that each of them provides. PARTNER CONTENT 3 Real-Life Electronics-Manufacturing Issues Resolved with MRP Software 3 Real-Life Electronics-Manufacturing Issues Resolved with MRP Software 08.10.2023 Electrification of Off-Highway Vehicles Electrification of Off-Highway Vehicles 08.10.2023 Demand for Smart Medical Applications Drives New Business Opportunities for Memory Chips Demand for Smart Medical Applications Drives New Business Opportunities for Memory Chips 08.09.2023 Figure 1: The four main types of electric motor (Source: [1]) Figure 1: The four main types of electric motor (Source: [1]) For a variety of applications, BLDC and PMSM motors, two types of brushless motors that are closely related, have grown in popularity. These motors do not require brushes or a commutator, making them more effective than brushed motors and significantly extending motor life. The brush/commutator interface in a brushed motor creates commutation, which is the process of switching current flow in the phases to produce a rotating magnetic field, which causes motion. Friction and arcing are both brought on by this interaction, both of which are undesirable. BLDC motors and PMSMs use an electronically generated rotating magnetic field to do away with the brushes and commutator. The voltages and currents provided to the phases are modulated using external circuits specifically designed to accomplish this task. Even though more complex, BLDC motors and PMSMs offer significant advantages over conventional brushed motors. Their electronic commutation techniques are more dependable, smaller, lighter, and quieter than brushed motors operating at the same speed, increasing energy efficiency by 20% to 30%. While in in brushed motors the windings are located on the rotor (which rotates), in brushless motors they are located on the stator (which is stationary). Brushes are not necessary because of how the permanent magnets and windings are arranged within the electric motor. An electronic controller is required to control the current going to the stator coils of BLDC motors or PMSMs. Compared to AC Induction motors, BLDC and PMSM motors allow precise speed control, are more suitable for variable-speed applications, and have superior speed versus torque characteristics.

This article describes how to design and build a low-noise, high-performance, low-cost brushed DC motor programmable speed regulator. The regulator is immune to the temperature, voltage, and motor load variation. Also, this circuit is not sensitive to the motor coil resistance, which allows using different motors in the same application without any adjustments. The described circuit is designed specifically for devices in which a low-power brushed DC motor is used and in which the stability of the motor speed and low noise are critical. The motor speed is pre-programmed and does not require trimming after assembly, though it is possible to reprogram it to a different speed via I2C. Unlike traditional circuits (see Figure 1), this design does not require any feedback sensor. In this case, the motor itself is a sensor. Other, more traditional designs (see Figure 2) are dependent on the motor coil resistance. Both require post-production trimming. Some applications (for example, audio applications) are very noise-sensitive. That makes any PWM motor controllers not suitable. Brushed DC Motor Programmable Speed Regulator Figure 1: Traditional DC motor speed controller with current sensor Brushed DC Motor Programmable Speed Regulator Figure 2: Traditional DC motor speed controller based on TDA7275A Every brushed DC motor produces interference when brushes switch from coil to coil. This is considered one of the biggest downsides of such a motor. Unfiltered, it can interrupt the normal work of the circuits powered from the same power source or simply situated close by. While it is possible to filter out to an acceptable level the interference using a capacitor connected in parallel to the motor (in some cases, ferrite coil in series), it is impossible to get rid of it completely. PARTNER CONTENT 3 Real-Life Electronics-Manufacturing Issues Resolved with MRP Software 3 Real-Life Electronics-Manufacturing Issues Resolved with MRP Software 08.10.2023 Electrification of Off-Highway Vehicles Electrification of Off-Highway Vehicles 08.10.2023 Demand for Smart Medical Applications Drives New Business Opportunities for Memory Chips Demand for Smart Medical Applications Drives New Business Opportunities for Memory Chips 08.09.2023 In the case of the design described in this document, the small leftover interference is used to determine the motor speed. In most cases, cheap, low-voltage, low-power brushed DC motors have three moving coils. Each of them produces interference in a form of spikes; thus, the frequency of the spikes is 3× the revolutions of the rotor. So by counting the spikes, it is possible to not only determine the speed but control it by automatically adjusting to a pre-programmed value. All this and more can be achieved by using the SLG47004, a versatile programmable mixed IC with only basic external components. See the schematic diagram in Figure 3.