JPH11346493A - Conduction controller for electric motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a larger motor output, while protecting switching elements against thermal breakdown. SOLUTION: Temperature sensors 19, 20, 21 are disposed as closely as possible to switching elements 12a, 13a, 14a of intense temperature rise among pairs of switching elements 12a, 12b, 13a 13b, 14a, 14b in respective drivers 12, 13, 14 of a three-phase SR motor 11. A drive current designated value generating circuit 22 of the SR motor 11 determines a drive current target value It which satisfies an output request signal Srq, and a drive current allowable value Ip for supplying a maximum drive current without causing thermal breakdown of the switching element, based on the highest temperature detected by the temperature sensors 19, 20, 21. If It<Ip, the It is delivered as a drive current designated value Ir to switching elements 23, 24, and if It>=Ip, the Ip is delivered as a drive current designated value Ir to the switching elements 23, 24.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply control device for an electric motor such as an electric motor for traveling of an electric vehicle, and more particularly to a switching element (gate-insulated bipolar device) for opening and closing a current supply line from a power supply to the electric motor. The present invention relates to an energization control device for an electric motor configured to protect a switching transistor such as a transistor) from thermal destruction.

[0002]

2. Description of the Related Art As a conventional apparatus of this kind, there is one described in, for example, Japanese Patent Application Laid-Open No. 7-194,941. In this conventional device, a temperature sensor is installed near a switching element that opens and closes a current supply line from a power supply to an electric motor, or a temperature sensor is installed inside the switching element, and the temperature detected by this temperature sensor is measured. A predetermined temperature (a temperature detected at the position of the temperature sensor when the temperature of the switching element is slightly lower than an upper limit temperature at which thermal destruction occurs when the temperature sensor is installed near the switching element; If the former is higher than the latter, it is slightly lower than the upper limit temperature of the switching element.) The drive current target value is reduced at a predetermined reduction ratio. Increases according to the difference between the temperature detected by the temperature sensor and the predetermined temperature, and when the temperature of the switching element reaches the upper limit temperature, the reduction ratio becomes 100% at the temperature detected by the temperature sensor, and the drive current target value Is set to zero.

[0003]

Since the temperature rise of the switching element increases as the driving current supplied to the electric motor increases, it is necessary to prevent the switching element from being thermally destroyed in the above-described conventional device. The reduction ratio is set so as to cope with the case where the maximum drive current is supplied. In this case, even when the detected temperature of the temperature sensor exceeds a predetermined temperature while a drive current smaller than the maximum value is being supplied, the drive current is reduced at the above-described reduction ratio. However, the temperature rise of the switching element when supplying a drive current smaller than the maximum value is smaller than the temperature rise when supplying the maximum drive current, and supplying a drive current smaller than the maximum value. Even if the temperature detected by the temperature sensor exceeds the predetermined temperature during the operation, the drive current is reduced at the same reduction ratio as when the maximum drive current is supplied, because the temperature of the switching element is lower than the upper limit temperature. Although there is no risk of thermal destruction, the drive current is limited to a small value to limit the motor output to a small value.

[0004] It is an object of the invention of claim 1 of the present application to provide a larger motor output while protecting a switching element from thermal destruction.

[0005]

According to a first aspect of the present invention, there is provided a switching element for opening and closing a current supply line from a power supply to an electric motor, and a current sensor for detecting an actual value of a driving current of the electric motor. A drive sensor that generates and outputs a drive current command value for the electric motor based on a temperature sensor disposed in proximity to the switching element, a signal indicating a request for output of the electric motor, and a temperature detected by the temperature sensor. Command value generating means, and switching element driving means for turning on / off the switching element so as to approximate the drive current command value output by the drive current command value generating means to the actual drive current value detected by the current sensor. In the electric motor energization control device comprising: A drive current target value for satisfying the request is determined based on a signal indicating the request to be performed, and the maximum value of the drive current that can be supplied without thermally destroying the switching element based on the temperature detected by the temperature sensor. A drive current allowable value is obtained. If the obtained drive current target value is less than the drive current allowable value, the drive current target value is output as the drive current instruction value. An electric motor energization control device configured to output an allowable value as the drive current instruction value.

[0006] The power supply control device having such a configuration obtains a drive current target value for satisfying the request based on a signal indicating a request for the output of the electric motor, and performs the switching based on the temperature detected by the temperature sensor. A drive current allowable value which is a maximum value of a drive current that can be supplied without thermally destructing the element is obtained.When the drive current target value is less than the drive current allowable value, the drive current target value is output as a drive current instruction value, and When the drive current target value is equal to or larger than the drive current allowable value, the drive current allowable value is output as the drive current instruction value, so that a larger motor output can be obtained while protecting the switching element from thermal destruction.

In the above power supply control device, the drive current instruction value generating means calculates and maps in advance various drive current allowable values corresponding to various detected temperatures of the temperature sensor and stores them in a memory. In addition to reading the allowable driving current value corresponding to the detected temperature from the memory, the allowable driving current value can be obtained by calculation from the temperature detected by the temperature sensor. In addition, a temperature sensor shall be installed for each switching element that opens and closes the current supply line from the power supply to each phase coil of the electric motor, and the highest temperature detected by these temperature sensors shall be the switching element temperature. Therefore, even when the electric motor is driven in a locked state (only one-phase coil is energized), the switching element can be protected from thermal destruction.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an energization control device 10 for a three-phase switched reluctance motor (hereinafter referred to as SR motor) 11 applied to an electric motor for traveling of an electric vehicle.
FIG. 3 is a block diagram showing the configuration of FIG. The energization control device 10
A pair of switching elements (IGB) for opening and closing a current supply line from the DC power supply B to the one-phase coil of the SR motor 11
T) a driver 12 including 12a and 12b, and a pair of switching elements (IGBT) 13 for opening and closing a current supply line from the DC power supply B to a two-phase coil of the SR motor 11
a, 13b and a pair of switching elements (IGBT) 14a, 14 for opening and closing a current supply line from the DC power supply B to the three-phase coil of the SR motor 11.
b, a current sensor 15 for detecting an actual value of the driving current of the one-phase coil of the SR motor 11 and outputting an analog signal (voltage) Ia1 representing the actual value,
A current sensor 16 that detects the actual value of the drive current of the two-phase coil of the motor 11 and outputs an analog signal (voltage) Ia2 representing the actual value, and detects the actual value of the drive current of the three-phase coil of the SR motor 11 Analog signal (voltage) I representing it
and a current sensor 17 that outputs a3.

The energization control device 10 further includes an SR motor 1
A rotation angle sensor 18 such as a resolver that detects a rotation angle of the first rotor and outputs a digital signal Ar representing the rotation angle, and a temperature rise due to energization of each phase coil among a pair of switching elements of each of the drivers 12 to 13. The switching elements 12a, 13a, and 14a are in contact with the driver side surface or the bottom surface as close as possible to the switching elements 12a, 13a, and 14a, and detects an analog signal (voltage) T representing the temperature at the same position.
Temperature sensor 1 that outputs s1, Ts2, and Ts3, respectively
9, 20, 21; a drive current command value signal (voltage) Ir1 for the one-phase coil of the SR motor 11; a drive current command value signal (voltage) Ir2 for the two-phase coil of the SR motor 11;
Drive current instruction value signal (voltage) for the three-phase coil of the motor 11
The driving current instruction value generation circuit 22 that outputs Ir3 and the analog signal Ia1 are compared with the driving current instruction value Ir1 so that the analog signal Ia1 approximates the analog signal Ir1 (the actual value of the one-phase coil driving current is The switching elements 12a and 12b are turned on / off (to approximate the indicated value).
The switching element drive circuit 23 to be turned off and the analog signal Ia2 are compared with the analog signal Ir2 so that the analog signal Ia2 is approximated to the analog signal Ir2 (the actual value of the drive current of the two-phase coil is approximated to the indicated value). As described above, the switching element driving circuit 24 for turning on / off the switching elements 13a and 13b and the analog signal Ia3 are compared with the analog signal Ir3 so that the analog signal Ia3 is approximated to the analog signal Ir3 (by using a three-phase coil). A switching element driving circuit 25 for turning on / off the switching elements 14a and 14b (to approximate the actual value of the driving current to the indicated value).

The drive current instruction value generation circuit 22 outputs a request signal (accelerator opening signal or the like) Srq for the output of the SR motor 11, an analog signal Ar output from the rotation angle sensor 18, and output signals from the temperature sensors 19 to 21. Analog signals Ts1, Ts2, and Ts3 are input. The drive current instruction value generation circuit 22 calculates the target torque Tt of the SR motor 11
microcomputer for calculating the rotation speed Sp of the SR motor 11, the target torque Ttq and the rotation speed S
Drive current target value It map corresponding to p, temperature sensor 1
It is included in the drive current allowable value map, the drive current target value It map, and the drive current allowable value Ip map that are the maximum values of the drive current that can be supplied without thermally destroying the switching element at the temperature detected by 9 to 20. A non-rewritable memory for storing an energization pattern (representing a drive current value for each rotation angle of the rotor) corresponding to the energization pattern number being used, a rewritable memory for storing the determined energization pattern for each phase, It is composed of a circuit for reading out a drive current value corresponding to the rotor rotation angle and outputting it as a drive current instruction value, and operates as shown in the flowchart of FIG.

In FIG. 2, when the power is turned on, first, initialization is executed in step S1, and then in step S2
, The request signal Srq, the output signal A of the rotation angle sensor 18
r, output signals Ts1, Ts of temperature sensors 19, 20, 21
Read s2 and Ts3. Next, at step S3, it is determined whether or not the state of the request signal Srq has changed. If there is a state change, at step S4, S is determined based on the request signal Srq.
The target value Ttq of the output torque of the R motor 11 is determined, and the torque change flag is turned on. Then step S
At S5, based on the output signal Ar of the rotation angle sensor 18, S
The rotation speed Sp of the R motor 11 is calculated, and then it is determined in step S6 whether the rotation speed SP has changed. If there is a change in the rotation speed SP, the output torque target value Ttq obtained in step S4 from the drive current target value map in step S7 and the motor rotation speed S obtained in step S5.
After reading the drive current target value It and the energization pattern number corresponding to P, the process proceeds to step S8. Step S6
If there is no change in the rotation speed as a result of the determination in step S7, step S7
It is determined whether or not there is a change in the target torque Ttq, that is, whether or not the torque change flag is on. If there is no change, the process returns to step S2.
Proceed to 8.

In step S8, the drive current target value It and the energization pattern number are read from the drive current target value It map. Then, in step S9, the maximum temperature among the detected temperatures Ts1, Ts2, and Ts3 of the temperature sensors 19 to 21 is detected. The temperature Ts is obtained, and then in step S10, the drive current allowable value Ip and the energization pattern number corresponding to the detected temperature Ts are read from the drive current allowable value Ip map. The drive current allowable value Ip map is created based on the drive current allowable value Ip with respect to the temperature sensor detected temperature Ts in FIG.
The drive current allowable value Ip is obtained by the following equation.

Ip = (Tj-Ts) /Von.Rth where Tj: upper limit temperature of the switching element Von: voltage between the emitter and collector when the switching element is on Rth: thermal resistance between the switching element and the on-sensor Next, at step S11 It is determined whether or not the drive current target value It is less than the drive current allowable value Ip. If so, the drive current instruction value Ir is set to the drive current target value It in step S12, and then the process proceeds to step S14. Otherwise, in step S13, the drive current instruction value Ir is set to the drive current allowable value Ip, and then the process proceeds to step S14.

In step S14, step S12
Alternatively, an energization pattern for each phase is generated based on the drive current instruction value Ir and the energization pattern number determined in S13, and then, in step S15, each phase drive current instruction value Ir1 is generated based on each phase energization pattern and the angle signal Ar. , Ir2, Ir
After outputting 3, the process returns to step S2.

Although each of the drivers 12, 13, and 14 shown in FIG. 1 includes a pair of switching elements as constituent elements, some electric motor drivers include only one switching element. The invention of this application can be applied to such an electric motor.

When the driver of the electric motor is arranged on the cooling plate and the cooling medium flows through the cooling plate, the flow of the cooling medium depends on the temperature detected by the temperature sensor. It is desirable to control the flow rate such that the higher the detected temperature, the greater the flow rate of the cooling medium.

[0017]

As described above, in the power supply control device for an electric motor according to the invention of the present application, the drive current target value for satisfying the request based on the signal indicating the request for the output of the electric motor is determined. A drive current allowable value that is the maximum value of the drive current that can be supplied without thermally destructing the switching element based on the temperature detected by the temperature sensor and the drive current target value is less than the drive current target value. The drive current target value is output as the drive current instruction value, and when the drive current target value is equal to or greater than the drive current allowable value, the drive current allowable value is output as the drive current instruction value. A larger motor output can be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an SR motor energization control device according to an embodiment of the present invention.

FIG. 2 is a flowchart showing an operation of the electronic control circuit in FIG.

FIG. 3 is a graph showing a relationship between a temperature detected by a temperature sensor in FIG. 1 and a drive current allowable value that can be supplied to a maximum without thermally destroying a switching element.

[Explanation of symbols]

Reference Signs List 10 energization control device 11 SR motors 12, 13, 14 driver 12a, 12b, 13a, 13b, 14a, 14b
Switching elements 15, 16, 17 Current sensor 18 Rotor angle sensor 19, 20, 21 Temperature sensor 22 Drive current command value generation circuit 23, 24, 25 Switching element drive circuit

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI H02P 7/05 H02P 7/00 501 (72) Inventor Yoshihide Suzuki 2-3-3 Showa-cho, Kariya-shi, Aichi Aisin Newha -Within Do Co., Ltd.

Claims (1)

[Claims] A switching element for opening and closing a current supply line from a power supply to the electric motor; a current sensor for detecting an actual value of a driving current of the electric motor; a temperature sensor disposed in proximity to the switching element; A drive current instruction value generating means for generating and outputting a drive current instruction value for the electric motor based on a signal indicating a request for an output of the electric motor and a temperature detected by the temperature sensor; A switching element driving unit for turning on / off the switching element so as to approximate the actual driving current value detected by the current sensor to the output driving current instruction value; Current instruction value generation means satisfies the request based on a signal indicating a request for an output of the electric motor. And a drive current allowable value that is a maximum value of a drive current that can be supplied without causing thermal damage to the switching element based on the temperature detected by the temperature sensor. When the value is less than the drive current allowable value, the drive current target value is output as the drive current instruction value, and when the drive current target value is equal to or greater than the drive current allowable value, the drive current allowable value is output as the drive current instruction value. An electric current control device for an electric motor, characterized in that: