• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    The present invention relates to a method of detecting a phase current of a motor, the method comprising: reading a phase current value N times in a predetermined cycle and summing the phase current value in a state where the motor is stopped, and obtaining a compensation value by dividing the summed phase current value by N; And after the motor operation, calculating the compensation value based on the read phase current value to detect the phase current, so that the offset can be corrected to obtain a more accurate phase current, and as a result, accurate motor control is possible.
    公开号:KR20030087698A
    申请号:KR1020020025558
    申请日:2002-05-09
    公开日:2003-11-15
    发明作者:황진성；김용태；김경훈；손창우
    申请人:엘지전자 주식회사；
    IPC主号:
    专利说明:

    Method for Detecting Phase Current in Motors
    [4] The present invention relates to a motor, and in particular, to a method of detecting a phase current of a motor.
    [5] In order to control the motor accurately, the current flowing through the motor must be measured so that the motor torque can be measured. In the related art, it has been proposed to use a plurality of current sensing resistors provided in a motor driving circuit so that current measurement of a conventional motor can be made. A single resistor is provided in series with each phase of the motor, and the voltage across each resistor is proportional to the current flowing through the resistor. However, this requires multiple current sensing circuits, one per resistor.
    [6] In general, for motors, especially motors used in motor products, it is very important to detect the magnitude of the phase current flowing through the motor in order to accurately control the motor. This is because almost all control algorithms of the RF inverter such as torque increase, slip compensation, stall prevention, and dead time compensation require information on the magnitude of the current. Electric motors which are usually used in industrial fields are three-phase induction motors, and therefore, the current in one phase is a sinusoidal AC signal having a three-phase symmetrical form.
    [7] As shown in FIG. 1, a general phase current detection circuit includes an inverter unit 12 supplying a phase current to the motor 11 through phase control, and a phase current detection unit sensing each phase current of the inverter unit 12 ( 13) and a processor 14 for converting and recognizing analog phase current values output from the phase current sensing unit 13 into digital and controlling the inverter accordingly.
    [8] Thus, the phase current detection method of the prior art configured as follows will be described.
    [9] In the related art, as shown in FIG. 2, the processor 14 is reset, the phase current is read at a predetermined cycle while the motor 11 is operated (S201), and converted to a digital value to be detected (S202).
    [10] Since the phase current detection method of the conventional motor includes elements such as an OP amplifier and a resistor due to the structural characteristics of the phase current sensing circuit, mismatching of a resistor and DC offset of the OP amplifier may occur. The fluctuation in the phase current detection value also occurs due to the change in the power supply voltage, resulting in deterioration of motor control performance.
    [11] Accordingly, an object of the present invention is to provide a phase current sensing method capable of accurately detecting phase current by appropriately compensating for errors in phase current sensing.
    [1] 1 is a circuit diagram showing a phase current sensing circuit of a typical motor
    [2] Figure 2 is a flow chart showing a phase current detection method of a conventional general motor
    [3] 3 is a flow chart showing a phase current detection method of the motor of the present invention.
    [12] In the phase current detection method of the motor of the present invention for achieving the above object, the step of reading the phase current value N times in a predetermined cycle in a state in which the motor is stopped and summing them, and adding the summed phase current value to And calculating the compensation value by dividing, and detecting the phase current by calculating the compensation value with the read phase current value after the motor operation.
    [13] Hereinafter, the phase current detection method of the motor of the present invention with reference to the accompanying drawings in detail as follows.
    [14] 3 is a flowchart illustrating a method of detecting a phase current of a motor of the present invention.
    [15] In the case of the general phase current sensing circuit described above, various elements such as an OP amplifier are connected to the phase current sensing unit. Such an OP amplifier has an offset output voltage with respect to an input, and a mismatch of resistance of each sensing stage through which current of each phase flows ( Mismatching also occurs, resulting in a higher sensing output than the actual current when the motor is running. For this reason, more than the allowable detection output occurs when the motor stops.
    [16] Therefore, the present invention is intended to perform accurate phase current measurement by compensating for a detection value abnormally output from the phase current sensing circuit of the motor when the motor is stopped.
    [17] That is, as shown in Figure 3, the phase current detection method of the motor of the present invention, first, the motor is turned off, the processor proceeds after the reset (S301).
    [18] Subsequently, the phase current is read N times at predetermined cycles, converted into digital values, and summed (S302). At this time, the predetermined period is, for example, 62.5 ms.
    [19] Then, the sum of the phase current values divided by N is calculated and stored (S303).
    [20] At this time, the phase currents are values output from each phase (R, S, T) of the motor. Therefore, after stopping the motor, the phase current values read N times are also sensed for each phase, and the compensation value is calculated for each phase.
    [21] As such, when the phase current values detected continuously N times are summed for each phase, the values accumulated for each phase are respectively (I r1 + I r2 + ..... + I rn = T_I r ), (I s1 + I s2 + ..... + I sn = T_I s ), (I t1 + I t2 + ..... = T_I t ).
    [22] When the accumulated phase current values are divided by N, the values T_I r / N, T_I s / N, and T_I t / N become compensation values.
    [23] The measurement of the phase current value N times after the motor stop is intended to reduce the degree of error by measuring N times and obtaining the average value because there is a high possibility that an error occurs in one phase current measurement.
    [24] In this way, after the calculation of the compensation value for each phase is completed, the motor is operated again (S304).
    [25] Subsequently, the phase current value is read for each phase at predetermined cycles (S305). The predetermined period here is the same as the period when N phase current values are measured to calculate the compensation value at the time of motor off. Therefore, it is 62.5 Hz.
    [26] The phase current value of each read phase R, S, and T is converted into a digital value I r , I s , I t , and the compensation value T_I r / N, T_I s / N, T_I t / N) is subtracted to detect each final phase current value (I r -T_I r / N, I s -T_I s / N, I t -T_I t / N) (S306).
    [27] In this case, the final phase current value is a phase current value at the time of motor operation, and is a value that can be used in a processor or a block requiring an actual phase current value.
    [28] The phase current detection method of the motor of the present invention as described above calculates in advance the error that may occur due to the elements constituted in the sensing circuit of the phase current as a compensation value, and subtracts the subsequent phase current detection, thereby reducing the By correcting the offset inevitably generated during the circuit connection of the component, a more accurate phase current can be obtained, and as a result, accurate motor control is possible.
    权利要求:
    Claims (3)
    [1" claim-type="Currently amended] Reading the phase current values N times in a predetermined cycle in a state where the motor is stopped and summing them up;
    Dividing the summed phase current value by N to obtain a compensation value;
    And detecting the phase current by calculating the compensation value based on the read phase current value after the motor operation.
    [2" claim-type="Currently amended] The method of claim 1, wherein the calculating of the compensation value comprises subtracting the compensation value from the phase current value read after the motor operation.
    [3" claim-type="Currently amended] The method of claim 1, wherein the phase current sensing is performed independently for each phase.
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    同族专利:
    公开号 | 公开日
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    法律状态:
    2002-05-09|Application filed by 엘지전자 주식회사
    2002-05-09|Priority to KR1020020025558A
    2003-11-15|Publication of KR20030087698A
    优先权:
    申请号 | 申请日 | 专利标题
    KR1020020025558A|KR20030087698A|2002-05-09|2002-05-09|Method for Detecting Phase Current in Motors|
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