JP4677592B2 - Operation method to prevent turbulence and step-out during low-speed and low-load operation when operating two or more PMSMs with one inverter - Google Patents

Description

  The present invention relates to a method for operating a PMSM (Permanent Magnet Synchronous Motor), more specifically, when a single inverter device is used to operate two or more PMSMs in a load state lower than the rated rotation, that is, at a low rotational speed. The present invention relates to an operation method that prevents turbulence and step-out occurring during operation.

Generally, in order to operate PMSM most efficiently during operation at the rated rotational speed, PMSM mainly employs direct axis current Id = 0 control (control in which the motor generated voltage and current are in phase). If the current is the minimum value.
None

  However, depending on the conditions under which PMSM is used, there are times when it is desired to operate PMSM at a lower rotation speed than the rated rotation speed. In such a case, since the load also becomes a light load that decreases in proportion to the cube of the rotation speed, the possibility of causing a step-out in the worst case increases. Further, there is a problem that even if it does not step out, turbulent vibration occurs and stable operation cannot be performed. In particular, when two or more PMSMs are operated in parallel by one inverter, the current value is greatly reduced, which is caused by the difference in internal phase difference angle due to a slight difference in characteristics of each load (for example, a blower fan). There has been a problem that vibration may occur and operation may become impossible.

  The present invention is a control method in a case where two or more PMSMs are operated by a single inverter in a low load state at a rotational speed lower than the rated rotational speed of the PMSM, and the two or more PMSMs are in a synchronized operation. The voltage value / current value generated by any one of the PMSMs is detected, and when the detected current value is equal to or less than the predetermined current value at which the PMSM's turbulent vibration and thus step-out occurs, the current value By increasing the advance angle (angle from the back electromotive force) and increasing the internal phase difference angle, it is possible to prevent turbulence / step-out of two or more PMSMs rotating synchronously. In addition, a rotor position detection device is provided in each of two or more PMSMs so that a signal of the rotor magnetic pole position of any one of the two or more PMSMs is detected, and the counter electromotive force ( The current value can be increased by changing the phase of the output voltage of the inverter to increase the internal phase difference angle between the voltage generated by the magnetic poles) and the output voltage of the inverter. By being able to do so, we tried to solve this problem.

  The present invention allows two or more PMSMs to be operated at a rotational speed substantially lower than the rated rotational speed by a single inverter device by an expensive position detection device or a simple control method that does not require sophisticated, complicated and time-consuming computation. There is an effect that the vehicle can be operated stably and silently without being distorted or stepped out.

  Because two or more PMSMs can be operated without turbulence / step-out even at low speeds with a single inverter device, the equipment cost can be realized at a lower cost compared to the case of 1C1M. Produces an effect.

  The present invention is a control system in which two or more PMSMs are operated in a low load state at a rotational speed lower than the rated rotational speed of the PMSM by an inverter using a single three-phase alternating current as a power source. When the voltage value / current value generated by any one of the PMSMs in the above synchronous operation is detected, and the detected current value is equal to or lower than the predetermined current value at which PMSM irregularity / step-out occurs, By increasing the lead angle of the current value and increasing the internal phase difference angle, a single inverter can be used for stable operation by preventing turbulence and step-out during low-load operation of two or more PMSMs. It is.

  Further, a rotor position detecting device is provided in each of two or more PMSMs, and a signal of a rotor magnetic pole position of any one of the two or more PMSMs is detected, and a counter electromotive force generated by the PMSMs is detected. By adjusting the output voltage of the inverter so that the internal phase difference angle between the output voltages of the inverters is increased, it is possible to prevent turbulence and step-out during low load operation of two or more PMSMs with one inverter. It was.

  As shown in FIG. 1, there is an operation of the blower fan 3 as one example of use when operating two or more PMSMs 2 with a single inverter device 1. Normally, PMSM2 is assumed to be operated at a rated rotational speed, but it may be desired to use the rotational speed at a reduced speed (70% or less of the rated rotational speed) depending on conditions. In this case, since the load torque decreases in proportion to the square of the rotational speed, the current required by the PMSM2 also decreases in proportion to the torque, which means that the PMSM internal phase difference angle δ decreases. When two or more PMSM2s are connected to one inverter 1, the current value is greatly reduced (about 25% at a rotation speed of 50%), and some characteristics of each fan fan load are The current value in each machine is based on the difference (a small difference in the fan fan load appears because the load torque is small) and the difference in internal phase angle due to the difference in impedance due to the difference in the length of the output cable of the inverter device 1 This causes a difference between the above and a turbulent vibration associated therewith, which may cause a stable operation and a step-out. Therefore, the current values of two or more PMSMs 2 in synchronous operation are detected at the output side of an IGBT (Insulated Gate Bipolar Transistor) circuit (not shown) of the inverter device 1 to detect the turbulence / step-out detected in advance. By using a calculation function that increases in the advance direction when the current value drops below a predetermined current value that is the limit point that occurs, avoiding PMSM2 turbulence or step-out by increasing the current angle advance angle and increasing the internal phase difference angle Therefore, it was designed to maintain a stable rotation even at a low rotation speed.

That is, as shown in the vector diagram of FIG. 2, the phase θ of the current supplied from the inverter device 1 is advanced from the back electromotive force of the PMSM 2, and the numerical value is 15 ° or more, preferably 20 ° or more. By increasing the internal phase difference angle δ, the current is increased, and two or more PMSMs 2 can be operated without being tuned or stepped out. When the current phase angle is advanced from the induced voltage, the internal phase difference angle δ increases to δ + Δδ, and the current value also increases. Since the torque is braked and reduced due to an increase in I ² R loss, etc., it is possible to prevent turbulence and thus step-out, and to suppress the occurrence of minute vibrations.

In the figure,
V ₀ ; Inverter output voltage (constant value)
E ₁ / E ₂ ; Back electromotive force (or induced voltage) of PMSM (before / after: constant value)
I ₁ / I ₂ ; Inverter output current (front / rear)
δ ₁ / δ ₂ ; Internal phase difference angle (front / rear)
θ ₁ / θ ₂ ; PMSM induced voltage and current phase difference (front / rear)
It is. I.e. the lead angle θ from I ₁ ^· a leading power factor cos [theta] ₁ ^· to I ₂ ^· of cos [theta] ₂ large west, it from becoming possible to the atmospheric and the internal phase difference angle to [delta] ₂ from [delta] _1.

In the case of a PMSM with a simple position detector, the back electromotive force (induced power, PMSM terminal power) generated by any one of two or more PMSMs connected to one inverter device is detected. By calculating, the internal phase difference angle between the counter electromotive force and the output voltage of the inverter device is increased to increase the output current of the inverter device, thereby preventing turbulence and step-out. By increasing the current to the PMSM, the minute torque is absorbed by increasing the I ² R loss and the internal phase difference angle is increased, so that the transition to the stable operating range can be ensured.

  The present invention can be widely used in a situation where two or more PMSMs operated by one inverter device are used at a low rotational speed in addition to the rated rotational speed.

Example circuit diagram Vector illustration

Explanation of symbols

1 is an inverter device 2 is PMSM
3 is a blower fan

Claims (2)

  A control method in which two or more PMSMs (permanent magnet synchronous motors) are operated by a single inverter in a low load state at a rotational speed lower than the rated rotational speed of the PMSM, and the two or more units are in synchronous operation. The voltage value / current value generated by any one of the PMSMs is detected, and when the detected current value falls below a predetermined current value at which PMSM turbulence / step-out occurs, the advance of the current value By increasing the angle and increasing the internal phase difference angle, two or more PMSMs can be operated at a low speed with a single inverter to prevent turbulence and step-out during low-load operation, thereby ensuring stable operation. An operation method for preventing turbulence and step-out during low speed and low load operation when operating two or more PMSMs with one inverter.   A rotor position detecting device is provided in each of two or more PMSMs to detect a signal of the rotor magnetic pole position of any one of the two or more PMSMs, and a counter electromotive force generated by the PMSM and an inverter The operation method according to claim 1, wherein the output current of the inverter is increased so as to increase the internal phase difference angle between the output voltages of the inverters.

Images