US 11,897,339 B2
Cart
Kunihisa Shima, Anjo (JP); Hitoshi Suzuki, Anjo (JP); and Ryo Umemoto, Anjo (JP)
Assigned to MAKITA CORPORATION, Anjo (JP)
Filed by MAKITA CORPORATION, Anjo (JP)
Filed on Jul. 1, 2022, as Appl. No. 17/856,340.
Claims priority of application No. 2021-117079 (JP), filed on Jul. 15, 2021.
Prior Publication US 2023/0023514 A1, Jan. 26, 2023
Int. Cl. B60L 15/30 (2006.01); B62B 5/00 (2006.01); B60L 3/00 (2019.01); B60L 15/20 (2006.01); H02P 5/74 (2006.01); H02P 3/22 (2006.01)
CPC B60L 15/2009 (2013.01) [B62B 5/0036 (2013.01); H02P 3/22 (2013.01); H02P 5/74 (2013.01); B60L 2240/421 (2013.01)] 4 Claims
OG exemplary drawing
 
1. A cart comprising:
a driving wheel;
a motor configured to rotate the driving wheel;
a motor drive circuit configured to drive the motor;
a motor brake circuit configured to electrically brake the motor;
a rotation speed sensor configured to detect a rotation speed of the motor; and
a control device configured to control the motor via the motor drive circuit and the motor brake circuit based on a target rotation speed of the motor and the rotation speed detected by the rotation speed sensor,
wherein
the motor brake circuit includes:
a semiconductor element configured to operate in a first mode and a second mode in response to a control input signal;
a resistor connected in series with the semiconductor element;
a current detection circuit configured to detect current flowing through the resistor; and
a comparator circuit configured to compare a current command value input from the control device and a current value detected by the current detection circuit to generate the control input signal,
brake current for electrically braking the motor flows in the semiconductor element,
when the semiconductor element operates in the first mode, the magnitude of the brake current changes substantially linearly when the control input signal changes,
when the semiconductor element operates in the second mode, the magnitude of the brake current changes less than the magnitude of the brake current changes in the first mode when the control input signal changes, and
the motor brake circuit is configured to operate the semiconductor element in the first mode when braking the motor.