Motor driving device, control method for motor driving device, and storage medium

Patent metadata

Field	Value
Publication number	US-11128232-B2
Application number	US-201816632387-A
Country	US
Kind code	B2
Filing date	Jul 25, 2018
Priority date	Jul 31, 2017
Publication date	Sep 21, 2021
Grant date	Sep 21, 2021

Abstract

A driving device is provided with an output unit, an input unit, a rectifier circuit, a switching circuit and a controller. The input unit inputs an AC in put. The rectifier circuit has a smoothing capacitor and converts the AC input into a rectified output. The switching circuit switches between an ON-state in which input impedance is low and an OFF-state in which input impedance is higher than that in the ON-state. The controller sets a start timing such that, when controlling the switching circuit to switch between the ON-state and the OFF-state, at least a portion of a period, in which the start timing of a power supply period becomes a second timing, is included in a period from a time when an input current inputted to the smoothing capacitor is generated to a time when the voltage of the smoothing capacitor reaches a maximum value.

First claim

The invention claimed is:

1. A motor driving device comprising:
an output unit configured to connect a motor;
an input unit configured to input an AC input voltage varying at a predetermined period between a positive voltage and a negative voltage;
a rectifier circuit configured to convert the AC input voltage input from the input unit into a rectified output which is one of the positive voltage and the negative voltage and include a smoothing capacitor that smooths the rectified output;
a motor control circuit configured to connect the smoothing capacitor and switch between an ON-state in which an input impedance viewed from the smoothing capacitor is low and an OFF-state in which an input impedance is higher than the input impedance in the ON-state at a switching period shorter than the predetermined period during a power supply period; and
a controller configured to:
vary a start timing with a variation in the rectified output between a predetermined timing at which a rotation angle of the motor becomes a predetermined angle of the motor or a first timing earlier than the predetermined timing and a second timing further earlier than the first timing; and
set the start timing of the power supply period such that at least a portion of a period, in which the start timing becomes the second timing, is included in a period from a time at which an input current input to the smoothing capacitor is generated to a time at which a voltage of the smoothing capacitor becomes a maximum when performing a control for switching between the ON-state and the OFF-state of the motor control circuit.

2. The motor driving device according to claim 1 , wherein the controller includes a measurement unit measuring a voltage of the rectified output.

3. The motor driving device according to claim 1 , wherein the smoothing capacitor is an electrolytic capacitor.

4. The motor driving device according to claim 1 , wherein the controller sets the start timing such that at least the portion of the period in which the start timing becomes the second timing is included in a period in which an absolute value of the voltage of the rectified output increases.

5. The motor driving device according to claim 1 , wherein the controller sets a variation in the start timing between the first timing and the second timing as a periodic variation deviating by a predetermined time from a periodic variation of the rectified output.

6. The motor driving device according to claim 5 , wherein the predetermined time is determined based on a frequency of the AC input.

7. The motor driving device according to claim 5 , wherein the controller sets the start timing based on a reciprocal of an absolute value of a previous voltage of the rectified output before the predetermined time.

8. The motor driving device according to claim 1 , wherein the controller periodically varies the start timing in a triangular waveform and sets a timing at which the start timing of a triangular waveform becomes a maximum value to a timing later than a timing at which an absolute value of the voltage of the rectified output becomes a minimum.

9. The motor driving device according to claim 1 , wherein the controller sets the start timing to the second timing from a time at which an absolute value of the voltage of the rectified output becomes a first voltage set near a minimum value of the absolute value of the voltage of the rectified output to a time at which an absolute value of the voltage of the rectified output becomes a second voltage set near a maximum value of the absolute value of the voltage of the rectified output.

10. The motor driving device according to claim 1 , wherein the controller sets the start timing to the second timing during a period in which an absolute value of the voltage of the rectified output increases.

11. The motor driving device according to claim 1 , wherein the motor control circuit is an inverter circuit.

12. The motor driving device according to claim 1 , wherein the controller varies the start timing by increasing or decreasing the power supply period.

13. The motor driving device according to claim 1 , wherein the controller performs a control for switching between the ON-state and the OFF-state of the motor control circuit while varying a duty ratio which is a ratio of a period in which the ON-state is maintained to the switching period with the variation in the rectified output between a first duty ratio and a second duty ratio greater than the first duty ratio, and sets the duty ratio such that at least a portion of a period in which the duty ratio becomes the second duty ratio is included in a period in which the input current input to the smoothing capacitor is generated and the voltage of the smoothing capacitor becomes a maximum at the time of control.

14. The motor driving device according to claim 1 , wherein the controller sets a duty ratio which is a ratio of a period in which the ON-state is maintained to the switching period based on a difference between a target power of the rectified output that is output to the output unit and an actual power of the rectified output.

15. The motor driving device according to claim 1 , wherein the controller sets a duty ratio which is a ratio of a period in which the ON-state is maintained to the switching period based on a difference between a target rotation speed of the motor and an actual rotation speed of the motor.

16. A control method for a motor driving device including an output unit that connects a motor, an input unit that inputs an AC input voltage varying at a predetermined period between a positive voltage and a negative voltage, a rectifier circuit that converts the AC input voltage input from the input unit into a rectified output which is one of the positive voltage and the negative voltage and includes a smoothing capacitor that smoothes smooths the rectified output, and a motor control circuit that connects the smoothing capacitor and switches between an ON-state in which an input impedance viewed from the smoothing capacitor is low and an OFF-state in which an input impedance is higher than the input impedance in the ON-state at a switching period shorter than the predetermined period during a power supply period, the control method comprising the steps of:
varying a start timing with a variation in the rectified output between a predetermined timing at which a rotation angle of the motor becomes a predetermined angle of the motor or a first timing earlier than the predetermined timing and a second timing further earlier than the first timing; and
setting the start timing of the power supply period such that at least a portion of a period, in which the start timing becomes the second timing, is included in a period from a time at which an input current input to the smoothing capacitor is generated to a time at which a voltage of the smoothing capacitor becomes a maximum when
performing a switching between the ON-state and the OFF-state of the motor control circuit.

17. A storage medium storing a program, wherein the program causes a computer to perform the control method according to claim 16 .

Assignees

• Nidec Corp

Inventors

• Kataoka Kotaro
• Iwata Hiroshi
• Suzuki Takamitsu
• Nomura Masaru

Classifications

• H02M3/33507

  with automatic control of the output voltage or current, e.g. flyback converters (H02M3/33561, H02M3/33569 take precedence) · CPC title

• H02P27/08

  with pulse width modulation · CPC title

• H02M7/53875 Primary

  with analogue control of three-phase output · CPC title

• H02M1/0058

  by employing soft switching techniques, i.e. commutation of transistors when applied voltage is zero or when current flow is zero (using an auxiliary actively switched resonant commutation circuit connected to an intermediate DC voltage or between two push-pull branches of an inverter bridge H02M7/4811; in resonant inverters H02M7/4815; in inverters operating from a resonant DC source H02M7/4826) · CPC title

• H02M1/007

  Plural converter units in cascade (push-pull DC/DC converters with pre-regulator H02M3/3374; DC-AC converters following a DC-DC stage including a high frequency transformer H02M7/4807; DC-AC converters following a DC-DC conversion stage generating periodically varying voltages H02M7/4826) · CPC title