JP3827118B2 - Power electronic circuit equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to power electronic circuit devices.
[0002]
[Prior art]
Semiconductor switching elements used in motor control inverter circuits, etc., may increase in temperature due to large current switching and break the junction, and are used by restricting the energization current to a predetermined current limit value or less. .
However, since the element temperature varies greatly depending on the heat dissipation conditions such as the outside temperature that the element should radiate, a temperature sensor is installed near the element to detect the element vicinity temperature so that the element vicinity temperature does not exceed the allowable maximum temperature Tmax. It has been proposed to limit the current.
[0003]
[Problems to be solved by the invention]
However, in the above-described power electronic circuit device that controls the temperature near the element, even if the temperature sensor is provided as close to the chip as possible, the temperature near the element detected by the temperature sensor is equal to the junction temperature Tj of the semiconductor switching element chip. Since there is a difference, although there is still a margin depending on the use conditions, there is a problem that current limitation is performed and performance is deteriorated.
[0004]
The present invention has been made in view of the above problems, and provides a power electronic circuit device capable of realizing an increase in output current without deteriorating element safety and without complicating the device structure. This is a problem to be solved.
[0005]
[Means for Solving the Problems]
According to a first configuration of the present invention, a total of six power modules in which a semiconductor chip on which a semiconductor switching element for power interruption is formed is fixed to a metal block, and the metal blocks of each power module are interposed via an insulating film. each a metallic base plate to be fixed, and the temperature sensor a total of six detecting individually the temperature of the vicinity of each of the semiconductor chips are fixed individually to the respective metal blocks close to individually to each semiconductor chip Te the comprising detection means for detecting a state quantity related to the current in the semiconductor switching element, and a current limiting means for limiting the current of the semiconductor switching element based the on both the temperature and the state, three-phase inverter circuit The power electronic circuit device is characterized in that:
In this configuration, the current limit of the semiconductor switching element is implemented based on the temperature near each semiconductor switching element detected by each temperature sensor and the state quantity related to the current of the semiconductor switching element.
[0006]
In this way, compared to slave coming technology, while ensuring the safety of the semiconductor switching devices, respectively, without complicating the device structure, it is possible to realize an increase in output current.
[0007]
Thereby, the effect of Claim 1 can be improved further.
According to the configuration of claim 3, in the configuration of claim 1, the current limiting means further stores in advance the relationship between the detected temperature and current and the junction temperature Tj of the semiconductor chip, and this relationship with the detected temperature. The allowable maximum value of current is obtained from the above, and the detected current is limited to the allowable maximum value or less.
[0008]
In this way, the operation and effect of the first aspect can be realized quickly and with high accuracy.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
The metal block of the power module can directly radiate heat to the outside air or indirectly radiate heat to the outside air through the cooling member.
Hereinafter, preferred embodiments of the present invention will be described based on the following examples.
[0010]
[Example 1]
An embodiment of the power electronic circuit device of the present invention will be described below with reference to FIG.
This power electronic circuit device 1 is a vehicle air-conditioning motor control device, which is configured to supply three-phase AC power to a compressor driving motor M of an air-conditioning device by intermittently connecting direct-current power from an in-vehicle battery (not shown). It comprises a phase inverter circuit 2, a gate controller 3 for applying a control voltage to the three-phase inverter circuit 2, and an air conditioning motor control controller 4 for controlling the gate controller 3 based on an input signal. Reference numeral 5 denotes a temperature sensor provided in the three-phase inverter circuit 2, and reference numeral 6 denotes a current sensor that detects an output current of the three-phase inverter circuit 2. As will be described later, the temperature sensor 5 is for detecting the temperature in the vicinity of the element in the three-phase inverter circuit 2, and the current sensor 6 detects the output current of the three-phase inverter circuit 2 and controls the controller 4 for air conditioning motor control. Output to. These three-phase inverter circuit 2, gate controller 3, air conditioning motor control controller 4, temperature sensor 5 and current sensor 6 are sealed in a case 7 shown in FIG.
[0011]
The three-phase inverter circuit 2 has exactly the same circuit configuration as that of the conventional one, and is composed of a total of six IGBT chips 212 and diodes (not shown) connected in antiparallel with these IGBT chips 212. The chip 212 constitutes the upper arm, and the three IGBT chips 212 constitute the lower arm. However, in FIG. 2, the IGBT module 21 that accommodates these IGBT chips 212 is schematically shown.
[0012]
As shown in FIG. 2, the case 7 includes a base plate 71 manufactured by aluminum die casting and a rectangular box-shaped aluminum cover 72 fixed to the base plate 71. The base plate 71 has a large number of cooling fins 73 parallel to each other on the outside, and each cooling fin 73 extends in the front-rear direction of the vehicle body in the engine room.
[0013]
The IGBT module 21 has a structure in which an IGBT chip 212 is mounted on a metal block 211 that forms a heat sink, and the bottom surface of the metal block 211 is fixed to the upper surface of the base plate 71 via an insulating film. Further, the temperature sensor 5 is provided on the metal block 211. As a result, the three-phase inverter circuit 2 incorporates a total of six temperature sensors 5.
[0014]
A heat dissipation system of one IGBT chip 212 will be described below.
Since the thermal resistance of the base plate 71 and the thermal resistance of the contact portion between the metal block 211 and the temperature sensor 5 are small, they are ignored, and the junction temperature of the IGBT chip 212 is Tj, and the vicinity of the element that the temperature sensor 5 detects If the temperature is Ts, the thermal resistance from the junction of the IGBT chip 212 to the temperature sensor 5 is r, and the calorific value at the junction is Q,
Tj = Q × r + Ts
If the amount of heat generation Q is regarded as the power loss P of the entire device, the power loss P is a function of the current I flowing through the IGBT chip 212 (a value proportional to the square value of I). If the time delay of heat transfer to the temperature sensor 5 is ignored, the junction temperature Tj is as shown in FIG.
[0015]
In FIG. 3, a characteristic line A of the junction temperature Tj indicates a case where the element vicinity temperature Ts is Ts1, and a characteristic line B of the junction temperature Tj indicates a case where the element vicinity temperature Ts is Ts2 higher than Ts1.
If the allowable maximum temperature Tmax of the junction temperature Tj is 125 ° C., the maximum value Ipmax of the current I that can flow when the element vicinity temperature Ts is Ts1 can be seen from the graph of FIG.
[0016]
A control operation of the air conditioning motor control controller 13 that performs current limitation based on the characteristics of FIG. 3 will be described with reference to FIG.
First, the rotation speed of the compressor is determined based on the air conditioning heat load, and the operation at the rotation speed is commanded to the gate controller 3 (s100).
Next, the output current I of the three-phase inverter circuit 2 is read from the current sensor 6 and the average value is calculated (s102), and the element vicinity temperature Ts is read from the temperature sensor 5 (s104).
[0017]
Next, based on the read average output current I and element vicinity temperature Ts, the junction temperature Tj is calculated from the built-in map or the above formula (s106), and it is checked whether the calculated junction temperature Tj is less than 125 ° C. ( If less, the operation at the rotation speed set in s100 is instructed to the gate controller 3 (s110). If more, the operation at the rotation speed lower than the set rotation speed by a predetermined value is performed by the gate controller. 3 and return to s100.
[0018]
In this way, the current is limited so that the junction temperature Tj estimated based on the output current I and the element vicinity temperature Ts does not exceed the allowable maximum temperature Tmax. An increase in output current can be realized without causing complication.
[0019]
[Example 2]
Another embodiment of the in-vehicle power electronic circuit device of the present invention will be described below with reference to FIG.
In this embodiment, since steps s100 and s106 in the control flowchart in the first embodiment are changed, only the changed points will be described.
[0020]
In s100, the duty ratio of the three-phase inverter circuit 2 is set based on the air conditioning thermal load calculated based on the difference between the passenger compartment temperature and the target temperature. It is assumed that the air conditioning motor controller 4 stores in advance the relationship between the difference between the passenger compartment temperature and the target temperature and the duty ratio.
In s206, an allowable maximum value Imax of the current I is obtained from the read element vicinity temperature Ts and a previously incorporated map (see FIG. 3) or a calculation formula corresponding thereto, and then the current I detected in s102 is the allowable maximum value. If it is greater than the value Imax, the duty ratio of the three-phase inverter circuit 2 is decreased by a predetermined amount (s210). If it is less, the duty ratio of the three-phase inverter circuit 2 is set to s100. A predetermined amount is increased within the set duty ratio range (s212).
[0021]
In this way, the same effect as Example 1 can be produced.
[Brief description of the drawings]
FIG. 1 is a block circuit diagram showing an embodiment of a power electronic circuit device of the present invention.
FIG. 2 is a partial cross-sectional view of the power electronic circuit device 1 shown in FIG.
FIG. 3 is a graph showing the relationship between the junction temperature Tj, current I, and element vicinity temperature Ts of the IGBT module 21;
FIG. 4 is a flowchart showing a control operation of an air conditioning motor control controller 4;
FIG. 5 is a flowchart showing a control operation of an air conditioning motor controller 4 in another embodiment.
[Explanation of symbols]
4 is a controller for air conditioning motor control (particularly, s110 and s210 are current limiting means), 5 is a temperature sensor, 6 is a current sensor (detection means), 211 is a metal block, 212 is an IGBT chip (a semiconductor switching element is formed) Semiconductor chip).

Claims (3)

A total of six power modules in which semiconductor chips on which semiconductor switching elements for power interruption are formed are fixed to a metal block;
A metal base plate to which the metal block of each power module is fixed via an insulating film;
Wherein a total of six temperature sensors for individually detecting the temperature of the vicinity of each of the semiconductor chips are fixed individually to the respective metal blocks close to individually to each semiconductor chip,
Detecting means for detecting a state quantity related to the current of the semiconductor switching element;
And current limiting means for limiting the current of the semiconductor switching element based the on both the temperature and the state,
With
A power electronic circuit device comprising a three-phase inverter circuit. The power electronic circuit device according to claim 1, wherein
The power electronic circuit device according to claim 1, wherein the current limiting means limits the current within a range in which the junction temperature Tj of the semiconductor chip obtained based on the temperature and the state quantity is equal to or lower than a predetermined allowable maximum temperature Tmax. The power electronic circuit device according to claim 1, wherein
The current limiting means stores the relationship between the detected temperature and current and the junction temperature Tj of the semiconductor chip, obtains an allowable maximum value of the current from the temperature and the relationship, and determines the detected current as the allowable maximum A power electronic circuit device characterized by being limited to a value.

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