Method for acquiring constant torque of electronically commutated motors

Patent metadata

Field	Value
Publication number	US-9831805-B2
Application number	US-201615353715-A
Country	US
Kind code	B2
Filing date	Nov 16, 2016
Priority date	Feb 12, 2015
Publication date	Nov 28, 2017
Grant date	Nov 28, 2017

Abstract

A method for acquiring a constant torque of an ECM, the method including: A) acquiring a target torque value T 0 input from external; B) when the motor is in a non-use state, operating the motor and acquiring an initial rotational speed rpm by the microprocessor; and when the motor is in an operating state, acquiring a current rotational speed rpm by the microprocessor; C) calculating a corresponding target bus current value Itad by the microprocessor using the function of a DC bus current Itad=F(T, rpm) according to the target torque T 0 and acquired rotational speed rpm, in which T represents a torque value output by the motor; and D) comparing the target bus current Itad with a real-time bus current Ibus by the microprocessor in a closed-loop control according to the detected real-time bus current Ibus.

First claim

The invention claimed is:

1. A method for acquiring a constant torque of an electronically commutated motor, the electronically commutated motor comprising:
a) a stator assembly,
b) a rotor assembly,
c) a housing assembly, and
d) a motor controller, the motor controller comprising: a microprocessor, an inverter circuit, and an operation parameter detecting circuit;
the operation parameter detecting circuit being configured to input operation parameters of the motor to the microprocessor; the microprocessor operating to output a pulse width modulation signal having a certain duty ratio to control the inverter circuit; and the inverter circuit operating to control operation of coil winding in each phase of the stator assembly;
the method comprising:
A) acquiring a target torque value TO input from external;
B) when the motor is in a non-use state, operating the motor and acquiring an initial rotational speed rpm by the microprocessor; and when the motor is in an operating state, acquiring a current rotational speed rpm by the microprocessor;
C) calculating a corresponding target bus current value Itad by the microprocessor using a function of a DC bus current Itad=F(T, rpm) according to the target torque TO and acquired rotational speed rpm, in which T represents a torque value output by the motor; and
D) comparing the target bus current Itad with a real-time bus current Ibus by the microprocessor in a closed-loop control according to the detected real-time bus current Ibus; when the target bus current value Itad is larger than the real-time bus current Ibus, increasing a duty ratio of the pulse width modulation signal output by the microprocessor; when the target bus current value Itad is smaller than the real-time bus current Ibus, reducing the duty ratio of the pulse width modulation signal; and when the target bus current value Itad is equal to the real-time bus current Ibus, stopping regulating the pulse width modulation signal, allowing the electronically commutated motor to enter a working state, and repeating B) for continuing a control state of the constant torque.

2. The method of claim 1 , wherein that the target bus current Itad is equal to the real-time bus current Ibus means that an error of a deviation of the real-time bus current Ibus from the target bus current Itad is within a range of 1%.

3. The method of claim 2 , wherein the function in C) is Itad=C×(rpm+A)/B, in which, C represents a constant, A=ƒ 1 (T), and B=ƒ 2 (T), and both A and B are functions for setting torque values T.

4. The method of claim 3 , wherein both A and B are first order functions for setting torque values T.

5. The method of claim 3 , wherein the function Itad=C×(rpm 30 A)/B is an equation for bus current under a control mode of the constant torque established by experiment means and is stored in the microprocessor.

6. The method of claim 1 , wherein the function in C) is Itad=C×(rpm+A)/B, in which, C represents a constant, A=ƒ 1 (T), and B=ƒ 2 (T), and both A and B are functions for setting torque values T.

7. The method of claim 6 , wherein both A and B are first order functions for setting torque values T.

8. The method of claim 6 , wherein the function Itad=C×(rpm +A)/B is an equation for bus current under a control mode of the constant torque established by experiment means and is stored in the microprocessor.

9. The method of claim 6 , wherein
A=K 0 +K 1 *T, in which, K 0 and K 1 are constants acquired from measurements, and T represents a torque output by the motor; and
B=D 0 +K 0 +K 1 *T, in which, D 0 represents a constant, and T represents the torque output by the motor.

10. The method of claim 6 , wherein
A=K 0 +K 1 *T, in which, K 0 and K 1 are constants acquired from measurements, and T represents a torque output by the motor; and
B=D 0 +K 0 +K 1 *T, in which, D 0 represents a constant, and T represents the torque output by the motor.

Assignees

• Zhongshan Broad Ocean Motor Co

Inventors

• Bian Wenqing

Classifications

• H02P23/0077

  Characterised by the use of a particular software algorithm · CPC title

• H02P6/08 Primary

  Arrangements for controlling the speed or torque of a single motor (H02P6/10, H02P6/28 take precedence) · CPC title

• H02P6/15

  Controlling commutation time · CPC title

• H02P27/08

  with pulse width modulation · CPC title

• H02P6/153

  wherein the commutation is advanced from position signals phase in function of the speed · CPC title