Sensorless Motor Control Technology

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Sensorless Motor Control Technology

With support from the government, E-bike has developed motor control technology without the use of a Hall sensor semiconductor. Hall sensors are easily affected by heat and vibration, and easily damaged by water intrusion. In addition, 3 sensors must be installed in each motor that require fine adjustments during installation, so lack of ease of use is a drawback.

Hall sensors detect motor position. In a method to detect the position of a sensorless motor which doesn’t have Hall sensors, since the motor itself produces electricity when it rotates, the amount of electricity changes greatly according to the rotation position. Based on observation of these differences, we determine the rotor position. This takes the place of the Hall sensor.

E-bike has developed sensorless motor control technology targeting the Chinese electric bicycle market, which has sales of 40 million units annually. This technology can be used in electric bicycles that are propelled via an accelerator, and also in electric assist bicycles used in Japan that have a motor activated during pedaling.

An electric bicycle must conduct everything smoothly from starting to normal operation. Unless the motor position is known when the bicycle is in a stopped state, the motor cannot propel the bicycle. This is extremely undesirable, as the motor does not act like a power generator when it is in a stopped state, and neither voltage nor current are generated. So we circulate a test current to determine motor position when it is in a stopped state. We have received three patents for technology that confirms motor position and rotation speed using a test current.

The Japanese electric assist bicycle market is over 500,000 units annually, and the European market is 2 million units annually. E-bike will first conduct sales in Japan, and for the future the company is planning to develop markets in Europe, North America, and Southeast Asia.

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