BLDC motors are becoming the mainstream in dishwashers, creating new opportunities for BLDC driver chip manufacturers

Statistics show that the market size of China's dishwasher industry will reach 12 billion yuan in 2023, an increase of 11.11% over the previous year. The cumulative retail volume in the first quarter of 2024 was 350,000 units, a year-on-year increase of 2.1%. The data shows that although the current dishwasher market is in an upward cycle, it has not yet reached the expectation of popularization by the public.

In 2023, the Chinese dishwasher market is still controlled by five companies, namely Siemens, Fotile, Midea, Robam Electric Appliances, and Haier Group, with a combined market share of 83.7%, and the industry market concentration is relatively high. In 2024, the competition in China's dishwasher market is still very fierce, and companies hope to attract more consumers through differentiated innovation. In this process, building dishwashers based on BLDC motors, and even equipping all series with BLDC motors as standard, has become the mainstream choice.

For example, Siemens dishwashers are almost all equipped with BLDC motors as standard, as well as 5D spray system + water softener + three-layer fine filtration system, which has been favored by many consumers.

Three common motors for dishwashers

At present, dishwashers on the market are mainly equipped with three types of motors, namely BLDC motors, asynchronous motors and brushed DC motors.

Among them, asynchronous motors are an AC motor whose speed under load is not a constant ratio to the frequency of the connected power grid. The basic characteristics of asynchronous motors are that the rotor winding does not need to be connected to other power sources, and its stator current is directly taken from the AC power system. Compared with other motors, asynchronous motors have a simple structure, are easy to manufacture, use and maintain, have high operating reliability, are light in weight and low in cost. Compared with DC motors of the same power and speed, asynchronous motors usually have more advantages in terms of volume and cost. However, most asynchronous motors are not efficient, and it is difficult to achieve high-precision motor control. Generally, smart dishwashers will not choose asynchronous motors.

Brushed DC motors use mechanical commutation, that is, brushes and commutators (or collector rings) are used to change the direction of the current, thereby driving the motor to rotate. This mechanical commutation method has friction and loss, and the brushes need to be replaced and maintained regularly. Different from BLDC, the brush device of brushless DC is used to introduce or extract voltage and current. The main structure is stator + rotor + brush, which obtains torque through rotating magnetic field and outputs kinetic energy. The brush and commutator are in constant contact and friction, which plays a role in conduction and commutation during rotation. However, brushless DC motors slide against each other, which will rub the carbon brushes, causing losses and making a lot of noise. In addition, due to irregular replacement of carbon brushes, the service life is relatively short. Therefore, high-end dishwashers rarely choose brushless DC motors at present.

BLDC consists of a motor body and a driver. Since it is operated in an automatic control mode, it will not add a starting winding to the rotor like a synchronous motor that starts under heavy load under variable frequency speed regulation, nor will it oscillate and lose steps when the load changes suddenly. This is because the BLDC motor does not have the brush and commutator structures of the brushless DC motor. The coil winding does not participate in the rotation but acts as a stator, and the permanent magnet acts as a rotor. The direction of the magnetic field is changed by controlling the direction of the coil current, so that the rotor continues to rotate. In comparison, BLDC motors have a long service life, low noise, and fast speed, but are relatively more expensive, making them the first choice for high-end smart dishwashers.

New opportunities for BLDC drive manufacturers

At present, high-end dishwasher products are mainly equipped with BLDC variable frequency motors. The utilization rate of variable frequency motors is twice that of ordinary motors. They are stable, quiet, can accurately control the washing power, and have a longer life than fixed frequency motors.

The rotor of the BLDC motor is a permanent magnet, which rotates by changing the direction of the magnetic field generated by the surrounding coils. The rotation of the rotor is controlled by controlling the direction and size of the current to the coil. Therefore, the drive circuit is an important part of the BLDC motor. At present, BLDC motors are very popular in air conditioners, refrigerators and washing machines. However, Chang Jianming, the chief engineer of Panasonic's home appliance motor research and development, once said, "From the current point of view, the proportion of permanent magnet BLDC motors in the field of home appliances will continue to grow." Part of the incremental demand comes from dishwashers, which has become a new opportunity for drive manufacturers.

From the perspective of drive control circuits, BLDC drive control circuits include MCU, full-bridge drive circuits, Hall feedback circuits, current sampling circuits, etc. If you look at the type, there are about four modes of BLDC motor drive architecture: DSP+peripheral drive+peripheral sampling, MCU+peripheral drive+peripheral sampling, dedicated MCU with pre-drive and sampling functions, and dedicated SoC chips. In terms of software implementation, square wave or sine wave (PMSM) control can be used. At present, BLDC driver ICs are still being updated.

For example, PI recently launched a new high-voltage integrated half-bridge (IHB) motor driver IC product series BridgeSwitch-2 to further enhance the software and hardware combination solution of BLDC. The BridgeSwitch-2 chip integrates the driver of the upper and lower tubes and two FREDFETs with enhanced performance. It uses lossless current detection internally and can provide up to 99% inverter efficiency. Because the IHB heating points are relatively concentrated, the PCB board size can be greatly reduced.

Of course, domestic chip manufacturers are currently very competitive in BLDC. For example, GigaDevice, Zhongying Electronics, Lingdong Shares, Lingou Chuangxin, China Micro Semiconductor, National Technology, Hangshun Chip, Xiaohua Semiconductor, Fengqi Technology and other manufacturers have some good products.

Conclusion

The white goods market is currently facing certain market challenges, and dishwashers are one of the few product categories that are experiencing positive growth. Currently, high-end dishwashers have basically turned to BLDC motors, which is a market opportunity for driver chips, which are expected to achieve better market results in the popularization of dishwashers.