阅读说明：本技术 功率转换装置 (Power conversion device ) 是由 栗原龙二 八幡光一 于 2020-03-13 设计创作，主要内容包括：本发明的功率转换装置中,将感温二极管(Td)设置在U相下臂半导体元件(Tul)附近。栅极控制电路(131)通过响应于由微机(151)输入的驱动信号向导通侧栅极电阻(Rg1)输出导通信号,从而使U相下臂半导体元件(Tul)导通。U相下臂半导体元件(Tul)的开关特性由导通侧栅极电阻(Rg1)和断开侧栅极电阻(Rg2)这两个构成的栅极电阻决定。将由温度检测部(14)检测温度的U相下臂半导体元件(Tul)的用于决定开关特性的栅极电阻的电阻值设定为相比于没有检测温度的其它半导体元件的用于决定开关特性的栅极电阻,由开关损耗引起的发热变大的值。(In the power conversion device of the present invention, a temperature sensing diode (Td) is provided in the vicinity of a U-phase lower arm semiconductor element (Tul). The gate control circuit (131) outputs an ON signal to the gate resistor (Rg1) on the conduction side in response to a drive signal inputted from the microcomputer (151), thereby turning on the U-phase lower arm semiconductor element (Tul). The switching characteristics of the U-phase lower arm semiconductor element (Tul) are determined by the gate resistance composed of both the on-side gate resistance (Rg1) and the off-side gate resistance (Rg 2). The resistance value of the gate resistance for determining the switching characteristic of the U-phase lower arm semiconductor element (Tul) for which the temperature is detected by the temperature detection unit (14) is set to a value at which the heat generation due to the switching loss is larger than the gate resistance for determining the switching characteristic of the other semiconductor element for which the temperature is not detected.)

1. A power conversion apparatus, comprising:

a power conversion circuit unit having a plurality of semiconductor elements that convert direct-current power into multiphase alternating-current power; and

a temperature detection unit for detecting a temperature of the semiconductor element corresponding to any one of the phases of the multiphase AC power,

the semiconductor element whose temperature is detected by the temperature detection unit is driven so that heat generation due to switching loss becomes larger than that of the other semiconductor elements whose temperature is not detected.

2. The power conversion apparatus according to claim 1,

the gate resistance for determining the switching characteristic of the semiconductor element whose temperature is detected by the temperature detection unit is set to a value at which heat generation due to switching loss is larger than the gate resistance for determining the switching characteristic of the other semiconductor element whose temperature is not detected.

3. The power conversion apparatus according to claim 1,

the capacitance between the gate and the emitter of the semiconductor element for which the temperature is detected by the temperature detection unit is set to a value at which switching loss is larger than the capacitance between the gate and the emitter of the other semiconductor element for which the temperature is not detected.

4. The power conversion apparatus according to claim 1,

the driving voltage of the driving circuit of the semiconductor element whose temperature is detected by the temperature detection unit is set to a value lower than the driving voltage of the driving circuit of the other semiconductor element whose temperature is not detected.

Technical Field

The present invention relates to a power conversion apparatus.

Background

The power conversion device has a semiconductor element for converting direct-current power into alternating-current power. As the semiconductor element, an IGBT (Insulated Gate Bipolar Transistor) or the like is used. A semiconductor element that switches a high voltage and a large current generates heat due to switching loss or the like. Therefore, a temperature detection element such as a temperature sensitive diode is provided near the semiconductor element to detect the temperature of the semiconductor element, and control is performed so that the semiconductor element does not exceed an allowable temperature. In the case of driving, for example, a three-phase motor, in the power conversion device, two semiconductor elements are used for each phase of the UVW phase, six semiconductor elements in total are used, and a plurality of temperature detection portions for the semiconductor elements of each phase are also required.

Patent document 1 describes a power converter including a temperature sensitive diode for detecting the temperature of one IGBT, and estimating the temperature of a semiconductor element whose temperature is not detected by calculation processing.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open No. 2012-186968

Disclosure of Invention

Technical problem to be solved by the invention

The device described in patent document 1 has a problem that a complicated calculation process for estimating the temperature is required.

Technical scheme for solving technical problem

The power conversion device of the present invention includes: a power conversion circuit unit having a plurality of semiconductor elements that convert direct-current power into multiphase alternating-current power; and a temperature detection unit for detecting a temperature of the semiconductor element corresponding to any one of the phases of the multi-phase ac power, wherein the power conversion device drives the semiconductor element whose temperature is detected by the temperature detection unit such that heat generation due to switching loss is greater than that of the other semiconductor elements whose temperature is not detected.

Effects of the invention

According to the present invention, the temperature detection unit is provided at the minimum necessary, and complicated calculation processing for estimating the temperature and the like are not required.

Drawings

Fig. 1 is a circuit configuration diagram of a power conversion apparatus.

Fig. 2 is a circuit diagram showing a main part of the drive circuit section.

Fig. 3(a) and 3(B) are graphs showing the relationship between the motor current and the temperature and loss.

Detailed Description

[ embodiment 1]

Fig. 1 is a circuit configuration diagram of a power conversion apparatus 1.

The power conversion device 1 is configured by a circuit having a semiconductor element for converting a direct current into an alternating current. The power conversion device 1 controls the driving of the motor 3 by switching the on and off of the semiconductor elements to flow a desired current using the battery 2 as a power source. Then, the dc power and the ac power are converted between the battery 2 and the motor 3. The battery 2 and the power conversion device 1 are connected by a relay 4. The upper control unit 5 is connected to the power conversion device 1.

The power conversion device 1 includes a power conversion circuit section 10 for performing power conversion, a capacitor 11 for filtering a direct current, a drive power supply section 12, a drive circuit section 13, a temperature detection section 14, and a control section 15. Power is supplied from the external power supply 6 to the control unit 15.

The power conversion circuit unit 10 has an upper and lower arm series circuit of UVW phase. The U-phase upper and lower arm series circuit is composed of a U-phase upper arm semiconductor element Tuu and a U-phase upper arm diode Duu, a U-phase lower arm semiconductor element Tul, and a U-phase lower arm diode Dul. The V-phase upper and lower arm series circuit is composed of a V-phase upper arm semiconductor element Tvu and a V-phase upper arm diode Dvu, a V-phase lower arm semiconductor element Tvl and a V-phase lower arm diode Dvl. The W-phase upper and lower arm series circuit is composed of a W-phase upper arm semiconductor element Twu and a W-phase upper arm diode Dwu, a W-phase lower arm semiconductor element Twl, and a W-phase lower arm diode Dwl.

The drive power supply unit 12 is connected to the positive electrode bus bar P and the negative electrode bus bar N for power supply, incorporates a DC-AC converter, a transformer, and an AC-DC converter, and outputs power supply voltages Vuu, Vvu, Vwu, Vul, Vvl, and Vwl of a drive circuit for driving the semiconductor elements of each phase.

The drive circuit section 13 includes: a drive circuit Guu to which a power supply voltage Vuu is supplied and which controls on/off of the U-phase upper arm semiconductor element Tuu; a drive circuit Gvu to which a power supply voltage Vvu is supplied and which controls on/off of the V-phase upper arm semiconductor element Tvu; and a drive circuit Gwu to which the power supply voltage Vwu is supplied and which controls on/off of the W-phase upper arm semiconductor element Twu. The drive circuit section 13 further includes: a driver circuit Gul to which a power supply voltage Vul is supplied and which controls on/off of the U-phase lower arm semiconductor element Tul; a drive circuit Gvl to which a power supply voltage Vvl is supplied and which controls on/off of the V-phase lower arm semiconductor element Tvl; and a drive circuit Gwl to which the power supply voltage Vwl is supplied and which controls the on/off of the W-phase lower arm semiconductor element Twl.

The temperature detector 14 includes a temperature detection circuit 141 for detecting a temperature based on the temperature sensing diode Td. In the present embodiment, the temperature sensing diode Td is disposed in the vicinity of the U-phase lower arm semiconductor element Tul, and the temperature sensing diode is not disposed in the vicinity of the other semiconductor elements.

The control unit 15 includes a microcomputer 151, receives an input of a current value supplied to the motor 3 detected by the current sensor 16, and outputs drive signals to the drive circuits Guu to Gwl in response to a command value from the host control unit 5. Further, the temperature detected by the temperature detecting portion 14 is input to the control portion 15, and the control portion 15 performs control so that the semiconductor element does not exceed the allowable temperature.

Fig. 2 is a circuit diagram showing a main part of the drive circuit section 13.

As shown in fig. 2, the temperature sensing diode Td is disposed in the vicinity of the U-phase lower arm semiconductor element Tul. The temperature detector 14 includes a temperature detection circuit 141 for detecting a temperature based on the temperature sensing diode Td, and the detected temperature is input to the microcomputer 151.

The microcomputer 151 outputs a drive signal to the drive circuit Gul. The driving circuit Gul includes a gate control circuit 131, an on-side gate resistor Rg1, an off-side gate resistor Rg2, and a gate-emitter capacitor Cge. The gate control circuit 131 and the temperature detection circuit 141 are supplied with the power supply voltage Vul from the driving power supply unit 12 as a driving power supply.

The gate control circuit 131 outputs an on signal to the turn-on side gate resistor Rg1 in response to a drive signal input from the microcomputer 151, thereby turning on the U-phase lower arm semiconductor element Tul. The gate control circuit 131 outputs a zero potential to the off-side gate resistance Rg 2.

Fig. 2 shows a drive circuit Gul for driving the U-phase lower arm semiconductor device Tul, and the drive circuits Guu and Gvu to Gwl of the other phases have the same configuration. However, in the present embodiment, as will be described later, the resistance values of the on-side gate resistor Rg1 and the off-side gate resistor Rg2 of the drive circuit Gul are different from the resistance values of the drive circuits Guu and Gvu to Gwl of the other phases. The capacitances of the capacitors Cge of the respective phases are all the same value.

The switching characteristics of the U-phase lower arm semiconductor element Tul are determined by the gate resistance formed by the on-side gate resistance Rg1 and the off-side gate resistance Rg 2. When the resistance value of the gate resistance is increased, the switching loss of the U-phase lower arm semiconductor element Tul increases, but the peak value of the surge voltage generated by switching decreases. In general, the resistance value of the gate resistor is set to minimize the switching loss in a range where the surge voltage does not exceed the rated voltage of the semiconductor element. In the present embodiment, the resistance value of the gate resistance for determining the switching characteristic of the U-phase lower arm semiconductor device Tul whose temperature is detected by the temperature detection unit 14 is set to a value that increases the heat generation due to the switching loss compared to the gate resistance for determining the switching characteristic of the other semiconductor device whose temperature is not detected. That is, the gate resistance of the U-phase lower arm semiconductor element Tul is increased to be higher than the temperature of the semiconductor element of the other phase, so that a phase with an increased switching loss is intentionally produced, and the temperature of the phase is detected.

The switching loss of the phase subjected to temperature detection is set in consideration of the deviation of temperature detection so that the minimum temperature value of the phase subjected to temperature detection is larger than the maximum temperature value of the phase not subjected to temperature detection.

It is considered that the cooling efficiency in the structure, the characteristics of the semiconductor element, and the characteristics of the temperature detection circuit are main factors causing the temperature detection deviation. Therefore, for example, when the temperature deviation is ± 10%, the switching loss of the phase for which the temperature detection is performed is increased, so that the temperature rises by + 20% or more.

Fig. 3(a) and 3(B) are graphs showing relationships among motor current, temperature, and loss when the present embodiment is applied.

In fig. 3(a), the motor current is shown on the horizontal axis, and the temperature is shown on the vertical axis. When the gate resistance of the U-phase lower arm semiconductor element Tul is increased so that its temperature becomes higher than that of the semiconductor element of the other phase, its temperature becomes higher than that of the other phase, for example, the W-phase. The temperature difference thereof increases in proportion to the magnitude of the motor current.

In fig. 3(B), the motor current is shown on the horizontal axis, and the loss is shown on the vertical axis. When the gate resistance of the U-phase lower arm semiconductor element Tul is increased to make the temperature higher than that of the semiconductor element of the other phase, the loss is higher than that of the other phase, for example, the W-phase. The loss difference thereof increases in proportion to the magnitude of the motor current.

According to the present embodiment, by detecting the temperature of the semiconductor element of the specific phase, it is possible to realize the over-temperature protection of the semiconductor element including the other phase at low cost while maintaining the reliability.

[ embodiment 2]

Next, embodiment 2 will be explained. The circuit configuration diagram of the power converter shown in fig. 1, the circuit configuration diagram of the drive circuit and the temperature detection unit shown in fig. 2, and the graphs of the temperature and loss of the U-phase and V-phase shown in fig. 3 are also the same in the present embodiment.

In the present embodiment, the capacitance of the capacitor Cge in the phase in which temperature detection is performed is set to be larger than the capacitance of the capacitor Cge in the other phase in which temperature detection is not performed, with respect to the capacitor Cge between the gate and the emitter shown in fig. 2. That is, the capacitance of the capacitor Cge is increased so that the temperature of the U-phase lower arm semiconductor element Tul becomes higher than the temperature of the semiconductor elements of the other phases, whereby a phase with increased switching loss is intentionally produced, and the temperature of the phase is detected. The gate resistances of the respective phases have the same resistance value.

In consideration of the variation in temperature detection, the switching loss of the phase subjected to temperature detection is set so that the minimum temperature value of the phase subjected to temperature detection is larger than the maximum temperature value of the phase not subjected to temperature detection.

It is considered that the cooling efficiency in the structure, the characteristics of the semiconductor element, and the characteristics of the temperature detection circuit are main factors of the temperature detection deviation. Therefore, for example, when the temperature deviation is ± 10%, the switching loss of the phase for which the temperature detection is performed is increased, so that the temperature rises by + 20% or more.

According to the present embodiment, by detecting the temperature of the semiconductor element of the specific phase, it is possible to realize the over-temperature protection of the semiconductor element including the other phase at low cost while maintaining the reliability.

[ embodiment 3]

Next, embodiment 3 will be explained. The circuit configuration diagram of the power converter shown in fig. 1, the circuit configuration diagram of the drive circuit and the temperature detection unit shown in fig. 2, and the graphs of the temperature and loss of the U-phase and V-phase shown in fig. 3 are also the same in the present embodiment.

In the present embodiment, the power supply voltage Vul supplied from the drive power supply unit 12 shown in fig. 1 to the drive circuit Gul is set to a voltage lower than the power supply voltages Vuu, Vvu, Vwu, Vvl, Vwl supplied to other drive circuits. By lowering the voltage, the switching loss using the gate resistance made up of the on-side gate resistance Rg1 and the off-side gate resistance Rg2 increases. That is, the drive circuit Gul is driven at a low voltage so that the temperature of the U-phase lower arm semiconductor element Tul is higher than the temperature of the semiconductor elements of the other phases, whereby a phase in which the switching loss is increased is intentionally produced, and the temperature of the phase is detected. The resistance value of the gate resistor and the capacitance of the capacitor Cge of each phase are the same.

In consideration of the variation in temperature detection, the switching loss of the phase subjected to temperature detection is set so that the minimum temperature value of the phase subjected to temperature detection is larger than the maximum temperature value of the phase not subjected to temperature detection.

It is considered that the cooling efficiency in the structure, the characteristics of the semiconductor element, and the characteristics of the temperature detection circuit are main factors of the temperature detection deviation. Therefore, for example, when the temperature deviation is ± 10%, the switching loss of the phase for which the temperature detection is performed is increased, so that the temperature rises by + 20% or more.

According to the present embodiment, by detecting the temperature of the semiconductor element of the specific phase, it is possible to realize the over-temperature protection of the semiconductor element including the other phase at low cost while maintaining the reliability.

According to the above-described embodiments, the following operational effects can be obtained.

(1) The power conversion apparatus 1 includes: a power conversion circuit unit 10 having a plurality of semiconductor elements for converting dc power into multiphase ac power; and a temperature detection unit 14 for detecting the temperature of the semiconductor element corresponding to any one phase of the multiphase ac power, wherein the power conversion device 1 drives the semiconductor element whose temperature is detected by the temperature detection unit 14 so that the heat generation due to the switching loss is larger than that of the other semiconductor elements whose temperature is not detected. Thus, the temperature detection unit is provided at the minimum necessary, and a complicated calculation process for estimating the temperature is not required.

(modification example)

The present invention can be implemented by modifying the above-described embodiments 1 to 3 as follows.

(1) In each embodiment, an example in which the temperature is detected for a specific one phase is described, but the temperature may be detected for a specific plurality of phases. In this case, control is performed so as not to exceed the allowable temperature based on the temperature of the higher one of the detected temperatures.

(2) The power conversion circuit units according to the respective embodiments have been described as examples applied to three phases, i.e., UVW phases, but the power conversion circuit units are not limited to three phases and may be applied to multiple phases.

The present invention is not limited to the above-described embodiments, and other embodiments that can be considered within the scope of the technical idea of the present invention are also included within the scope of the present invention as long as the features of the present invention are not impaired. Further, the above embodiment and a plurality of modifications may be combined.

Description of the reference symbols

1 power conversion device

2 batteries

3 electric motor

4 Relay

5 Upper control part

6 external power supply

10 power conversion circuit part

11 capacitor

12 drive power supply unit

13 drive circuit part

14 temperature detecting part

15 control part

16 current sensor

131 grid control circuit

141 temperature detection circuit

151 microcomputer

Tuu-phase upper arm semiconductor device

Tu 1U-phase lower arm semiconductor element

Tvu V-phase upper arm semiconductor device

Tv 1V phase lower arm semiconductor element

Twu W-phase upper arm semiconductor device

Tw 1W phase lower arm semiconductor element

Duu U phase upper arm diode

Du 1U-phase lower arm diode

Dvu V phase upper arm diode

Dv 1V phase lower arm diode

Dwu W-phase upper arm diode

Dw 1W phase lower arm diode

Capacitor between Cge gate and emitter

Td temperature sensing diode

Rg1 conducting side gate resistor

Rg2 off-side gate resistor

Guu, Gvu, Gwu, Gul, Gvl, Gwl driver circuits.