Electrical angle detecting device and synchronous motor drive device

• US 5,854,548 A
• Filed: 02/27/1997
• Issued: 12/29/1998
• Est. Priority Date: 02/29/1996
• Status: Expired due to Term

• Current Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Inventors: Taga, deceased, Yoshiaki, Taga, heiress, Tomoyo, Kawabata, Yasutomo, Taga, heir, Shigeo, Taga, heiress, Takiko
• Primary Examiner(s): Ro, Bentsu
• Application Number:
  US08/807,633
• Time in Patent Office: 670 Days
• Field of Search: 318/138, 318/254, 318/439, 318/700, 318/720, 318/721, 318/722, 318/724
• US Class Current: 318/721
• CPC Class Codes: H02P 6/185 using inductance sensing, e.g. pulse excitation

Abstract

An electrical angle detecting device for detecting the electrical angle of a synchronous motor utilizes differences in inductance between phases with the angle of a rotor 50 to determine electrical angle. Voltage is applied across predetermined phases, the currents Iu, Iv, Iw flowing through U, V, W phases as a function of the differing inductance with angle of the rotor 50 are simultaneously detected, and the electrical angle is determined from relationships among the three currents stored in memory beforehand. In a first stage, the electrical angle is determined in the 0-π range or the π-2π range by an approximation calculation and in a second stage the asymmetry of the maximum currents produced by the voltage applied across the phases is utilized to ascertain the range in which the electrical angle falls. the electrical angle can thus be unambiguously ascertained to enable sensorless detection of rotor position (electrical angle) even when the rotor is at rest or is rotating slowly.

Claims

1. An electrical angle detecting device of a synchronous motor whose rotor is driven to rotate by interaction between a magnetic field produced by windings upon passage of polyphase currents therethrough and a magnetic field produced by permanent magnets, said electrical angle detecting device comprising:

memory means for storing in advance relationships between electrical angle and behavior of currents passing through polyphase windings in response to a prescribed voltage applied to a combination of said polyphase windings through which currents pass,

voltage applying means for applying said voltage to said combination, said voltage including only one voltage pulse used for detecting an electrical angle,

current behavior detecting means for detecting said behavior of said currents passing simultaneously through each of said polyphase windings in a range of 0 to 2π

in response to said only one voltage pulse applied by said voltage applying means as a unique combination of electric currents passing through said polyphase windings, and

electrical angle computing means for determining said electrical angle of said motor between 0 and 2π

based on said behavior of said currents in said windings detected by said current behavior detecting means by referring to said relationships stored in said memory means.

2. An electrical angle detecting device of a synchronous motor whose rotor is driven to rotate by interaction between a magnetic field produced by windings upon passage of polyphase currents therethrough and a magnetic field produced by permanent magnets, said device comprising:

memory means for storing in advance relationships between electrical angle and behavior of currents passing through polyphase windings in response to a prescribed voltage applied to a combination of said polyphase windings through which currents pass,

voltage applying means for applying a voltage to said combination for shorter than a time period required for a change in electrical angle of π

, said time period being a function of an upper limit speed of said motor subjected to electrical angle detection, said voltage including only one voltage pulse used for detecting an electrical angle,

current behavior detecting means for detecting said behavior of said currents passing simultaneously through each of said polyphase windings in response to said only one voltage pulse which has been applied,

angle detecting means for determining said electrical angle of said motor in a 0-π

range or a π

-2π

range thereof based on said behavior of said currents in said windings detected by said current behavior detecting means by referring to said relationships stored in said memory means,

range ascertaining means for at least once ascertaining in which of said 0-π

range and said π

-2π

range said electrical angle falls, and

electrical angle update means for determining an initial value of said electrical angle from said detected electrical angle and a result of ascertaining by said range ascertaining means in the range 0-2π and

updating said current electrical angle using said electrical angle detected thereafter by said angle detecting means.

3. An electrical angle detecting device according to claim 2 wherein said voltage applying means is means for applying voltage of a magnitude smaller than that which produces current causing said windings to magnetically saturate in a prescribed time period.

4. An electrical angle detecting method for detecting an electrical angle of a synchronous motor whose rotor is drive to rotate by interaction between a magnetic field produced by windings upon passage of polyphase currents therethrough and a magnetic field produced by permanent magnets, said method comprising:

(a) applying a prescribed voltage to a combination of polyphase windings of said synchronous motor through which currents pass and in advance storing in memory relationships between electrical angle and behavior of currents passing through said polyphase windings in response to said applied voltage,

(b) applying a voltage, which includes only one voltage pulse used for detecting an electrical angle, to said combination,

(c) detecting said behavior of said currents passing simultaneously through each of said polyphase windings in a range of 0 to 2π

in response to said only one voltage pulse which has been applied as a unique combination of electrical currents passing through said polyphase windings, and

(d) determining said electrical angle of said motor between 0 and 2π

based on said detected behavior of said currents in said windings by referring to said relationships stored in memory.

5. An electrical angle detecting method for detecting an electrical angle of a synchronous motor whose rotor is driven to rotate by interaction between a magnetic field produced by windings upon passage of polyphase currents therethrough and a magnetic field produced by permanent magnets, said method comprising:

(a) applying a prescribed voltage, which includes only one voltage pulse used for detecting an electrical angle, to a combination of polyphase windings through which currents pass a plurality of times and in advance storing in memory relationships between electrical angle and corresponding behavior of currents passing through said polyphase windings in response to said voltage applied a plurality of times,

(b) repeatedly applying said voltage, which includes only one voltage pulse used for detecting an electrical angle, to said combination for a time period shorter than that required for a change in electrical angle of π

, said time period being a function of an upper limit speed of said motor subjected to electrical angle detection,

(c) detecting said behavior of said currents passing simultaneously through each of said polyphase windings in response to each of said only one voltage pulse which has been applied by said step of repeatedly applying,

(d) determining said electrical angle of said motor in a 0-π

range or a π

-2π

range thereof based on said detected behavior of said currents in said windings by referring to said relationships stored in memory,

(e) at least once ascertaining in which of said 0-π

range and said π

-2π

range said electrical angle falls, and

(f) determining an initial value of said electrical angle from said detected electrical angle and a result of ascertaining by said range ascertaining step in the range 0-2π and

updating said current electrical angle using said electrical angle detected thereafter.

6. An electrical angle detecting method according to claim 5, wherein said application of said voltage in step (b) is conducted by applying a voltage to said windings of a magnitude smaller than that which produces current causing said windings to magnetically saturate in a prescribed time period.

7. A synchronous motor drive device of a synchronous motor whose rotor is driven to rotate by interaction between a magnetic field produced by windings upon passage of polyphase currents therethrough based on an electrical angle of said rotor and a magnetic field produced by permanent magnets, comprising:

memory means for storing in advance relationships between electrical angle and behavior of currents passing through polyphase windings in response to a prescribed voltage applied to a combination of said polyphase windings through which currents pass,

voltage applying means for applying said voltage to said combination, said voltage including only one voltage pulse for detecting an electrical angle,

current behavior detecting means for detecting said behavior of said currents passing through each of said polyphase windings in a range of 0 to 2π

in response to said only one voltage pulse applied by said voltage applying means as a unique combination of electric currents passing through said polyphase windings,

electrical angle computing means for determining said electrical angle of said motor between 0 and 2π

based on said behavior of said currents in said windings detected by said current behavior detecting means by referring to said relationships stored in said memory means,

torque command value inputting means for inputting a torque command value related to torque required of said synchronous motor, and

current controlling means for controlling current passed through said polyphase windings based on said electrical angle determined by said electrical angle computing means and said input torque command value.

8. A synchronous motor drive device of a synchronous motor whose rotor is driven to rotate by interaction between a magnetic field produced by windings upon passage of polyphase currents therethrough based on an electrical angle of said rotor and a magnetic field produced by permanent magnets, comprising:

memory means for storing in advance relationships between electrical angle and behavior of currents passing through polyphase windings in response to a prescribed voltage applied to a combination of said polyphase windings through which currents pass,

voltage applying means for applying said voltage to said combination, said voltage including only one voltage pulse for detecting an electrical angle, for shorter than a time period required for a change in electrical angle of π

, said time period being a function of an upper limit speed of said motor subjected to electrical angle detection,

current behavior detecting means for detecting said behavior of said currents passing through each of said polyphase windings in response to said only one applied voltage pulse,

angle detecting means for determining said electrical angle of said motor in a 0-π

range or a π

-2π

range thereof based on said behavior of said currents in said windings detected by said current behavior detecting means by referring to said relationships stored in said memory means,

range ascertaining means for at least once ascertaining in which of said 0-π

range and said π

-2π

range said electrical angle falls, and

electrical angle update means for determining an initial value of said electrical angle from said detected electrical angle and a result of ascertaining by said range ascertaining means in the range 0-2π and

updating said electrical angle using said electrical angle detected thereafter by said angle detecting means,

torque command value inputting means for inputting a torque command value related to torque required of said synchronous motor, and

current controlling means for controlling current passed through said polyphase windings based on said electrical angle updated by said electrical angle update means and said input torque command value.

9. A synchronous motor drive method of a synchronous motor whose rotor is driven to rotate by interaction between a magnetic field produced by windings upon passage of polyphase currents therethrough based on an electrical angle of said rotor and a magnetic field produced by permanent magnets, said method comprising:

applying a prescribed voltage to a combination of polyphase windings through which currents pass and in advance storing in memory relationships between electrical angle and corresponding behavior of currents passing through said polyphase windings in response to said applied voltage,

applying said voltage to said combination which includes only one voltage pulse for detecting an electrical angle,

detecting said behavior of said current passing simultaneously through each of said polyphase windings in a range of 0 to 2π

in response to said only one applied voltage pulse as a combination of electric currents passing through said polyphase windings,

determining said electrical angle of said motor between 0 and 2π

based on said detected behavior of said currents in said windings by referring to said relationships stored in memory, and

controlling current passed through said polyphase windings based on said determined electrical angle and a torque command value for said motor.

10. A synchronous motor drive method of a synchronous motor whose rotor is driven to rotate by interaction between a magnetic field produced by windings upon passage of polyphase currents therethrough based on an electrical angle of said rotor and a magnetic field produced by permanent magnets, said method comprising:

applying a prescribed voltage to a combination of polyphase windings through which currents pass and in advance storing in memory relationships between electrical angle and corresponding behavior of currents passing through said polyphase windings in response to said voltage applied a plurality of times,

repeatedly applying said voltage which includes only one voltage pulse used for detecting an electrical angle to said combination for a time period shorter than that required for a change in electrical angle of π

, said time period being a function of an upper limit speed of said motor subjected to electrical angle detection,

detecting said behavior of said current passing simultaneously through each of said polyphase windings in response to each of said only one voltage pulse which has been applied by said step of repeatedly applying,

determining said electrical angle of said motor in a 0-π

range or a π

-2π

range thereof based on said detected behavior of said currents in said windings by referring to said relationships stored in memory,

at least once ascertaining in which of said 0-π

range and said π

-2π

range said electrical angle falls,

determining an initial value of said electrical angle from said detected electrical angle and a result of ascertaining by said range ascertaining step in the range 0-2π and

updating said electrical angle using said electrical angle detected thereafter, and

controlling current passed through said polyphase windings based on said updated electrical angle and a torque command value for said motor.