Multi-phase motor control apparatus and electric power steering apparatus using the same

• US 9,362,860 B2
• Filed: 10/11/2013
• Issued: 06/07/2016
• Est. Priority Date: 04/17/2013
• Status: Active Grant

• Current Assignee: NSK Limited
• Original Assignee: NSK Limited
• Inventors: Kumagai, Hiroyasu, Sugawara, Takayoshi, Imamura, Yousuke
• Primary Examiner(s): Ip, Paul
• Application Number:
  US14/240,656
• Publication Number:
  US 20160072421A1
• Time in Patent Office: 970 Days
• Field of Search: 318/400.02, 318/400.04, 318/432, 318/443, 318/446, 180/443, 701/42
• US Class Current: 1/1
• CPC Class Codes: B62D 5/046 Controlling the motor
• CPC Class Codes: B62D 5/0472 for damping vibrations
• CPC Class Codes: H02P 21/22 Current control, e.g. using a current control loop
• CPC Class Codes: H02P 23/14 Estimation or adaptation of motor parameters, e.g. rotor time constant, flux, speed, current or voltage
• CPC Class Codes: H02P 6/10 Arrangements for controlling torque ripple, e.g. providing reduced torque ripple
• CPC Class Codes: H02P 6/15 Controlling commutation time
• CPC Class Codes: H02P 6/28 Arrangements for controlling current H02P6/10 takes precedence

Abstract

A control device for a multiple motor comprises: a drive unit constituted by a pair of upper and lower arm switching elements for driving the multiphase motor; a single current detection circuit for detecting a current value; a PWM signal generation unit for generating a plurality of first phase PWM signals within two control cycles on the basis of the current value and a carrier signal; a phase shift control unit for shifting a first PWM signal with a prescribed phase generated by the PWM signal generation unit by gradually changing the amount of phase shift within the two control cycles, and outputting the shifted first PWM signal to the drive unit; and a current detection observer for estimating a current value for the multiphase motor on the basis of the current value. The PWM signal generation unit generates a plurality of second phase PWM signals within two control cycles on the basis of the estimated current value and carrier signal. When the phase shift amount in a prescribed phase in the control cycle immediately before the present control cycle is zero and the phase shift amount in a prescribed phase in the present control cycle is not zero, the phase shift control unit gradually increases the shift amount from zero in the present control cycle and the next control cycle to thereby use the second phase PWM signals in the next control cycle.

Claims

1. A multi-phase motor control apparatus comprising:

a driving section comprising pairs of upper-stage arm switching elements and lower-stage arm switching elements, and driving a multi-phase motor;

a single type current detection circuit detecting current values of said multi-phase motor;

a PWM-signal generating section generating plural first each-phase PWM-signals within two control periods based on said current values detected by said current detecting circuit and a carrier signal;

a phase shift control section shifting a first PWM-signal of a predetermined phase, which is generated in said PWM-signal generating section, by gradually changing a phase shift amount within two control periods, and outputting said shifted first PWM-signal to said driving section; and

a current detection observer estimating a current estimation value of said multi-phase motor based on said current values detected by said current detection circuit;

wherein said PWM-signal generating section generates plural second each-phase PWM-signals within two control periods based on said current estimation value and said carrier signal; and

wherein in a case that a phase shift amount of a predetermined phase in a just before control period is zero and a phase shift amount of a predetermined phase in a present control period is not zero, said phase shift control section gradually increases said phase shift amount from zero in said present control period and a next control period, and uses said second each-phase PWM-signals in said next control period.

2. The multi-phase motor control apparatus according to claim 1, wherein said phase shift control section calculates a phase shift amount to a final shift position of said first PWM-signal, and shifts by “

phase shift amount/n”

as a shift number is n times.

3. The multi-phase motor control apparatus according to claim 2, wherein with respect to said phase shift of said determined phase, shift times m (<

n) are performed in said present control period and rest (n-m) times are performed in said next control period.

4. The multi-phase motor control apparatus according to claim 1, wherein said current detection observer estimates a current value in said present control period based on a current value detected in a previous control period.

5. An electric power steering apparatus provided with said multi-phase motor control apparatus according to claim 1.

6. A multi-phase motor control apparatus comprising:

a driving section comprising pairs of upper-stage arm switching elements and lower-stage arm switching elements, and driving a multi-phase motor;

a single type current detection circuit detecting current values of said multi-phase motor;

a PWM-signal generating section generating plural first each-phase PWM-signals within two control periods based on said current values detected by said current detecting circuit and a carrier signal;

a phase shift control section shifting a first PWM-signal of a predetermined phase, which is generated in said PWM-signal generating section, by gradually changing a phase shift amount within two control periods, and outputting said shifted first PWM-signal to said driving section; and

a current detection observer estimating a current estimation value of said multi-phase motor based on said current values detected by said current detection circuit;

wherein said PWM-signal generating section generates plural second each-phase PWM-signals within two control periods based on said current estimation value and said carrier signal; and

wherein in a case that a phase shift amount of a predetermined phase in a just before control period is not zero and a phase shift amount of a predetermined phase in a present control period is zero, said phase shift control section gradually decreases said phase shift amount to zero in said present control period and a next control period, and uses said second each-phase PWM-signals in said next control period.