阅读说明：本技术 电机驱动装置及制冷循环应用设备 (Motor driving device and refrigeration cycle application equipment ) 是由 畠山和德 植村启介 清水裕一 于 2018-02-28 设计创作，主要内容包括：一种电机驱动装置,具备能够驱动各自在转子具有永久磁铁的n台(n为2以上的整数)电机(41、42)的逆变器(4)、以及切换n台电机的连接状态的连接切换部(8),其中,使连接切换部(8)工作,改变与所述逆变器4连接的电机的台数,从而使从逆变器观察电机侧的阻抗变化。也可以在n台电机中的i台(i为2至n中的任一个)电机由逆变器同时驱动的情况下,控制逆变器输出的电压,以使i台电机的电感值相互一致。能够防止因由逆变器驱动的多台电机的相位差引起的振荡及失步。(A motor drive device is provided with an inverter (4) capable of driving n motors (41, 42) each having a permanent magnet on a rotor thereof (n is an integer of 2 or more), and a connection switching unit (8) for switching the connection state of the n motors, wherein the connection switching unit (8) is operated to change the number of motors connected to the inverter (4), thereby changing the impedance of the motor side as viewed from the inverter. In the case where i (i is any one of 2 to n) motors among the n motors are simultaneously driven by the inverter, the voltage output from the inverter may be controlled so that the inductance values of the i motors match each other. Oscillation and step-out due to phase difference of a plurality of motors driven by an inverter can be prevented.)

1. A motor drive device is provided with:

an inverter capable of driving n motors each having a permanent magnet on a rotor, n being an integer of 2 or more; and

a connection switching unit for switching the connection state of the n motors,

the connection switching unit is operated to change the number of motors connected to the inverter 4, thereby changing the impedance of the motor side as viewed from the inverter.

2. The motor drive apparatus according to claim 1,

the impedance of the motor side viewed from the inverter is inversely proportional to the number of motors connected to the inverter.

3. The motor drive device according to claim 1 or 2,

further comprises a control unit for controlling the inverter and the connection switching unit,

when i motors of the n motors are simultaneously driven by the inverter, the output voltage of the inverter is controlled so that the inductance values of the i motors match each other, i being any one of 2 to n.

4. The motor drive device according to claim 1 or 2,

further comprises a control unit for controlling the inverter and the connection switching unit,

when j motors among the n motors are simultaneously braked by the inverter, the inverter is controlled to output voltages so that inductance values of the j motors coincide with each other, and then the braking operation is switched to, where j is any one of 2 to n.

5. The motor drive apparatus according to any one of claims 1 to 4,

the n motors are respectively embedded magnet synchronous motors.

6. The motor drive apparatus according to any one of claims 1 to 5,

the connection switching section is formed of a wide bandgap semiconductor.

7. The motor drive apparatus according to any one of claims 1 to 5,

the connection switching unit is constituted by an electromagnetic contactor.

8. The motor drive apparatus according to any one of claims 1 to 7,

the switching element or the free wheel diode constituting the inverter is formed of a wide bandgap semiconductor.

9. A refrigeration cycle application apparatus comprising the motor drive device according to any one of claims 1 to 8.

10. The refrigeration cycle applying apparatus according to claim 9, wherein,

the heat exchanger of the refrigeration cycle applying apparatus has n sections,

the n motors are provided corresponding to the n parts,

switching a portion of the n portions that performs a heat exchange operation according to a load of the refrigeration cycle applying apparatus,

the n motors are driven by the inverters when the heat exchanger portion corresponding thereto performs a heat exchange operation.

11. The refrigeration cycle applying apparatus according to claim 10, wherein,

the driving of each of the n motors by the inverter is started after the heat exchange operation of the portion of the heat exchanger corresponding to the motor is started.

12. The refrigeration cycle applying apparatus according to claim 10, wherein,

the driving of each of the n motors by the inverter is started before a heat exchange operation of a portion of the heat exchanger corresponding to the motor is started.

13. The refrigeration cycle applying apparatus according to claim 10, 11 or 12, wherein,

the driving of each of the n motors by the inverter is stopped after the heat exchange operation of the portion of the heat exchanger corresponding to the motor is stopped.

14. The refrigeration cycle applying apparatus according to claim 10, 11 or 12, wherein,

the driving of each of the n motors by the inverter is stopped before the heat exchange operation of the portion of the heat exchanger corresponding to the motor is stopped.

Technical Field

The present invention relates to a motor drive device and a refrigeration cycle application apparatus including the motor drive device.

Background

Conventionally, there are techniques as follows: when two or more Permanent Magnet Synchronous Motors (PMSM) are driven by a single inverter device, a voltage value and a current value generated in any one of the PMSM are detected, and when the detected current value is equal to or less than a predetermined current value, the lead angle of the current is increased to increase the current, thereby preventing hunting and step-out (for example, patent document 1).

Disclosure of Invention

Problems to be solved by the invention

In the technique described in patent document 1, when the synchronous motor is not a surface magnet type motor but an embedded magnet type motor, reluctance torque due to a difference between d-axis inductance and q-axis inductance is generated, and therefore, when the lead angle of the current is increased, the output torque of the motor becomes large, and when the same torque is output, the current is decreased, and therefore, the possibility of hunting and step-out becomes large instead.

The present invention has been made in view of the above circumstances, and an object thereof is to prevent hunting and step-out due to phase differences of a plurality of motors driven by the same inverter.

Means for solving the problems

In order to solve the above problem, a motor drive device according to the present invention includes:

an inverter capable of driving n motors (n is an integer of 2 or more) each having a permanent magnet on a rotor; and

a connection switching unit for switching the connection state of the n motors,

the connection switching unit is operated to change the number of motors connected to the inverter 4, thereby changing the impedance of the motor side as viewed from the inverter.

Effects of the invention

According to the present invention, it is possible to prevent hunting and step-out due to phase differences of a plurality of motors driven by the same inverter.

Drawings

Fig. 1 is a schematic diagram showing a configuration example of a motor drive device according to embodiment 1 of the present invention.

Fig. 2 is a block diagram showing a configuration example of the control unit of fig. 1.

Fig. 3(a) to (c) are diagrams showing operations of the PWM signal generation unit of fig. 2.

Fig. 4 is a diagram showing the relationship between the current lead angle and the magnet torque, reluctance torque, and resultant torque.

Fig. 5 is a diagram showing a difference in lead angle in the case where there is a difference in rotational phase between two motors.

Fig. 6(a) and 6(b) are waveform diagrams showing phase inductances and induced voltages in the case where rotational phases are different between two motors.

Fig. 7(a) and 7(b) are waveform diagrams showing phase inductances and induced voltages in the case where rotational phases of two motors match.

Fig. 8 is a diagram showing a configuration example of a motor drive device according to embodiment 2 of the present invention.

Fig. 9 is a functional block diagram showing a configuration example of the control unit of fig. 8.

Fig. 10 is a circuit configuration diagram showing a heat pump apparatus according to embodiment 3 of the present invention.

Fig. 11 is a mollier chart showing a state of the refrigerant in the heat pump apparatus shown in fig. 10.

Detailed Description

Hereinafter, a motor driving device and a refrigeration cycle application apparatus including the motor driving device according to an embodiment of the present invention will be described with reference to the drawings. The present invention is not limited to the embodiments described below.