JP2024022927A - semiconductor equipment - Google Patents

Abstract

An object of the present invention is to accurately calculate the temperature of an element constituting a semiconductor device and protect the element from overheating. [Solution] A control unit Cnt of an inverter 1 calculates a counter value acquired at a predetermined time from parameters that affect heat generation of switching elements Q1 to Q6, and calculates a counter value obtained from the results of temperature sensors Ts1 and TS2. By adding them, a limiting current is calculated so that the estimated element temperature does not exceed a predetermined temperature. As parameters, an element temperature variable X(n) corresponding to the temperature of the switching elements Q1 to Q6 themselves, and a simulator that simulates the temperature rise of a part that is thermally connected to the switching elements Q1 to Q6 and has a large heat capacity in response to the temperature rise of the element. temperature variable ΔY(n). The control unit Cnt calculates the counter upper limit value Z_limit(n) based on the element temperature variable X(n) and the simulated temperature variable ΔY(n) from the current values detected by the current detection units Si1 and Si2. [Selection diagram] Figure 7

Description

The present invention relates to a semiconductor device.

Elements that constitute a semiconductor device are easily affected by temperature. For example, semiconductor devices used to control the rotation of drive motors of industrial vehicles such as forklifts require high output. In addition, while the drive motor is generally stopped during cargo handling, the drive motor is rotated at a relatively high speed while the vehicle is traveling, so the output changes significantly over time. Therefore, the amount of heat generated by the elements constituting the semiconductor device frequently fluctuates up and down.

Therefore, the temperature of the elements constituting the semiconductor device is measured using a temperature sensor or the like, and the elements are protected from overheating based on the measured temperature.

For example, a technique has been proposed for an inverter device that performs a predetermined protective operation when the junction temperature of a power semiconductor element for each PWM carrier cycle estimated by a temperature estimation calculation unit exceeds a predetermined value (see Patent Document 1). ).

JP2018-46647A

In order to protect the elements that make up a semiconductor device from overheating, you can place multiple temperature sensors that measure the temperature of the elements that make up the semiconductor device, or place the temperature sensor in an ideal location such as near the element you want to measure. By doing so, it is possible to accurately measure the temperature of the element to be protected against overheating.

However, when the number of temperature sensors is increased, although the accuracy of measured temperature can be expected to improve to some extent, it results in an increase in cost. Further, depending on restrictions on product layout such as the configuration of a semiconductor device, it may not be possible to arrange the temperature sensor at an ideal location, and the temperature of the element may not be accurately measured. Due to constraints on the number and layout of temperature sensors, the element temperature and the value of the temperature sensor may deviate, and the actual state of the element temperature may become unclear. As a result, the accuracy of temperature measurement deteriorates, and the element may not be sufficiently protected from overheating.

An object of one aspect of the present invention is to accurately calculate the temperature of an element constituting a semiconductor device and protect the element from overheating.

A semiconductor device according to one embodiment of the present invention includes an element constituting the semiconductor device, a temperature measuring means for measuring the temperature generated by the element, a current detecting section for detecting a current flowing through the element, and a current detecting section for detecting a current flowing through the element. and a control section that controls the element. The control unit calculates a counter value obtained at a predetermined time from a parameter that affects heat generation of the element, and adds it to the counter value obtained from the result of the temperature measuring means, so that the estimated element temperature becomes a predetermined temperature. The limit current is calculated so as not to exceed the current limit. The parameters include an element temperature variable that corresponds to the temperature of the element itself, and a simulated temperature variable that simulates the temperature rise of a portion that is thermally connected to the element and has a large heat capacity in response to a temperature rise of the element. The control unit includes a counter increment extraction unit that calculates a limit current based on the element temperature variable and the simulated temperature variable from the current value detected by the current detection unit.

As a result, the control unit simulates the temperature variable corresponding to the temperature of the element itself and the temperature rise of a part that is thermally connected to the element and has a large heat capacity based on the current value detected by the current detection unit. The limiting current can be calculated based on the simulated temperature variable. Therefore, the limited current can be calculated based on the minimum number of temperature measuring means, taking into account the response delay due to the temperature difference between the temperature measuring means and the element, in addition to the temperature of the element itself. Thereby, it is possible to improve the accuracy of temperature measurement while suppressing an increase in cost. As a result, the temperature of the elements constituting the semiconductor device can be calculated with high accuracy, and the elements can be protected from overheating.

Further, the arrangement direction of the elements and the extending direction of a plate of a heat sink that cools the elements may be the same direction, and the temperature measuring means may be arranged upstream and downstream of the heat sink.

Thereby, the elements can be arranged with high density, and the influence of the obtained value measured by the temperature measuring means can be suppressed.

Further, the control unit may have a counter upper limit value used to calculate the limited current, and may be able to set a margin coefficient corresponding to a margin of temperature rise used to calculate the limited current.

This makes it possible to easily adjust parameters such as margin coefficients corresponding to the margin of temperature rise when developing the device for multiple uses. As a result, it is possible to reduce design man-hours.

According to the present invention, it is possible to accurately calculate the temperature of an element constituting a semiconductor device, and to protect the element from overheating.

1 is a diagram showing an example of a semiconductor device according to an embodiment of the present invention. FIG. 3 is a perspective view showing the relationship between a temperature sensor and a switching element. It is a graph showing the relationship between counter value Z(n) and current value. It is an example of the flowchart which shows the process which calculates a limit current. This is an example of a table showing the relationship between variables and current. This is an example of a table showing the relationship between variables and current. It is an example of a graph showing the relationship between counter value Z(n) and current value.

Embodiments will be described in detail below based on the drawings.

FIG. 1 is a diagram showing an example of a semiconductor device according to an embodiment of the present invention.

In FIG. 1, an inverter 1 is shown as a semiconductor device. The inverter 1 includes a control section Cnt, switching elements Q1 to Q6, temperature sensors Ts1 and Ts2, current detection sections Si1 and Si2, and a capacitor C.

Switching elements Q1 to Q6 are examples of elements constituting a semiconductor device. MOSFETs (metal-oxide-semiconductor field-effect transistors) are used as the switching elements Q1 to Q6. However, an IGBT (Insulated Gate Bipolar Transistor) or the like may be used as the switching element. Switching elements Q1 to Q6 each include diodes D1 to D6. The six diodes D1 to D6 are parasitic diodes of the six switching elements (MOSFETs) Q1 to Q6, respectively.

A switching element Q1 forming the u-phase upper arm and a switching element Q2 forming the u-phase lower arm are connected in series between the positive electrode bus Lp and the negative electrode bus Ln. A switching element Q3 forming a v-phase upper arm and a switching element Q4 forming a v-phase lower arm are connected in series between the positive electrode bus Lp and the negative electrode bus Ln. A switching element Q5 forming a w-phase upper arm and a switching element Q6 forming a w-phase lower arm are connected in series between the positive electrode bus Lp and the negative electrode bus Ln.

By configuring the inverter 1 with a MOSFET and a parasitic diode of the MOSFET, the configuration of the semiconductor device can be created with a simpler configuration than configuring it with a mechanical switch or the like, and the size of the semiconductor device can be reduced.

The connection point between switching element Q1 and switching element Q2 is connected to the u-phase input terminal of motor M, the connection point between switching element Q3 and switching element Q4 is connected to the v-phase input terminal of motor M, and switching element Q5 and A connection point with switching element Q6 is connected to a w-phase input terminal of motor M.

With the switching operations of the switching elements Q1 to Q6 that make up the upper and lower arms, the DC power supplied from the power storage device B can be converted into three-phase AC power with a phase difference of 120 degrees and supplied to the motor M. ing. The motor M is, for example, a vehicle drive motor or a cargo handling motor.

A control unit Cnt is connected to the gate terminal of each of the switching elements Q1 to Q6. The control unit Cnt causes the switching elements Q1 to Q6 of the inverter 1 to perform switching operations based on a pulse pattern that is a control signal.

The current detection unit Si1 is connected to the v-phase input terminal of the motor M, and detects the current supplied from the inverter 1 to the motor M through the v-phase. The current detection unit Si2 is connected to the w-phase input terminal of the motor M, and detects the current supplied from the inverter 1 to the motor M through the w-phase. The control unit Cnt controls the inverter based on the current supplied to the motor M through the v phase detected by the current detection unit Si1 and the current supplied to the motor M through the w phase detected by the current detection unit Si2. The current supplied to motor M through phase 1 to u is detected. Thereby, the control unit Cnt can detect the current supplied from the inverter 1 to the motor M.

The temperature sensor Ts1 and the temperature sensor Ts2 are examples of temperature measuring means. Unless the temperature sensor Ts1 and the temperature sensor Ts2 are specifically explained separately, they will also be referred to as "temperature sensor Ts" hereinafter. The temperature sensor Ts measures the temperature of elements such as MOSFETs that constitute the inverter 1.

The temperature sensor Ts may be placed near the switching elements Q1 to Q6 that make up the inverter 1 to measure the temperature of the components of the switching elements Q1 to Q6 such as MOSFETs that make up the inverter 1. Further, the temperature sensor Ts may be placed directly next to the switching elements Q1 to Q6 such as MOSFETs to directly measure the temperature of the switching elements Q1 to Q6. The temperature sensor Ts and the switching elements Q1 to Q6 are thermally connected to each other. Heat transfer connection refers to a state in which the elements are connected so that heat can be transmitted through an object or space, and a state in which the heat of the switching elements Q1 to Q6 can be transferred to the temperature sensor Ts by heat conduction, convection, radiation, etc. say.

FIG. 2 is a perspective view showing the relationship between temperature sensors Ts1, Ts2 and switching element Q1. As shown in FIG. 2, the inverter 1 is placed on a heat sink Hs. The heat sink Hs is composed of a plurality of plate-like bodies P extending in the same direction. In this embodiment, the direction in which the plate-like body P extends is defined as the upstream and downstream sides of the heat sink Hs. The heat sink Hs cools the switching elements Q1 to Q6 that constitute the inverter 1.

As shown in FIG. 2, the temperature sensor Ts1 and the temperature sensor Ts2 are arranged in the same direction as the extending direction of the plate-like body P constituting the heat sink Hs, and on the upstream and downstream sides of the heat sink Hs (in the extending direction of the heat sink Hs). , end side). As a result, the switching elements Q1 to Q6 can be arranged with high density, and the influence of the obtained values based on the difference in thermal resistance and heat capacity obtained by the temperature sensor Ts1 and the temperature sensor Ts2 can be suppressed to a minimum. .

The control unit Cnt calculates the counter value Z(n) acquired at a predetermined time from the parameters that affect the heat generation of the switching elements Q1 to Q6, and calculates the counter value Z(n) obtained from the temperature acquired from the temperature sensor Ts1 and the temperature sensor Ts2. Calculate by adding to the value. The control unit Cnt indicates the estimated element temperature value of the temperature rise of the switching elements Q1 to Q6 based on the output current. The counter value Z(n) is the amount of temperature rise of the switching elements Q1 to Q6 for each count period. The counter value Z(n) is acquired at a predetermined time. For example, the estimated value of the temperature of the switching element Q1 is determined by Equation 1 below.

Measured temperature T1 measured by temperature sensor Ts1 + counter value Z(n) = estimated value of temperature of switching element Q1...Equation 1

The parameter indicates the effective value of the current detected by the current sensor in the interval from current I(n)=t(n-1) to t(n). In Equation 1 above, the measured temperature T1 measured by the temperature sensor Ts1 is estimated, but the estimation is not limited to this. For example, in Equation 1, by substituting the measured temperature T2 measured by the temperature sensor Ts2 instead of the measured temperature T1 measured by the temperature sensor Ts1, the measured temperature T2 measured by the temperature sensor Ts2 can be similarly calculated. can be used to calculate an estimated value of the temperature of the switching element.

FIG. 3 is a graph showing the relationship between counter value Z(n) and current value. The counter value on the vertical axis is a value that is proportional to the temperature. The current value is the current flowing through the inverter 1. The current value may be a current flowing through the inverter 1 via the switching elements Q1 to Q6.

The counter value Z(n) indicates the current count cycle (n), that is, the counter value at the nth count. The counter value Z(n-1) indicates the counter value at the previous (n-1) count cycle, that is, the (n-1)th count period. The counter upper limit value Z_limit(n) indicates the counter threshold value at the n-th counter cycle. The counter upper limit value Z_limit(n) is a value used to determine the current that can be calculated in the flowchart illustrating the process of calculating the limit current described in FIG. 4.

FIG. 4 is an example of a flowchart showing the process of calculating the limited current. When calculating the limit current, the control unit Cnt functions as a counter increase amount extraction means. In this case, the control unit Cnt calculates the limit current based on the temperature variable X(n) and the simulated temperature variable Y(n) from the current values detected by the current detection units Si1 and Si2. Specifically, the control unit Cnt implements current limitation in the following steps, for example, according to the flowchart of FIG. 4. First, the control unit Cnt calculates a count-up value based on the current flowing from the previous time (n-1st time) to the current time (nth time) (step S1). Then, the control unit Cnt calculates a limiting current so that the temperature does not exceed from this time (nth time) to the next time (n+1th time) (step S2).

The control unit Cnt can continue to calculate the limit current by repeatedly performing the processes of step S1 and step S2. The control unit Cnt can protect the switching elements Q1 to Q6 from overheating by limiting the current based on the calculated limit current.

Specifically, the control unit Cnt uses the estimated counter value to calculate the current counter value Z(n) using Equation 2 below.
Counter value Z(n)=X(n)+Y(n-1)+ΔY(n)...Formula 2

X(n) is a variable (element temperature variable) that simulates a temperature rise in a portion with a small heat capacity (such as inside the element). X(n) is a variable corresponding to the temperature of the element itself.
ΔY(n) is a variable (simulation temperature variable) that simulates the temperature rise of a portion having a large heat capacity (from the element to the temperature sensor, etc.) that is heat-conductively connected to the element that corresponds to the temperature rise of the element. X(n) is calculated from the table shown in FIG. 5(1). ΔY(n) is calculated from the table shown in FIG. 5(2).

FIG. 5 is an example of a table showing the relationship between variables and current. Current I(n) indicates the effective value of the current detected by the current detection units Si1 and Si2 in the interval from t (n-1st time) to t (nth time). Y(n-1) indicates the previous (n-1th) counter value. ΔY(n) indicates the amount of increase in the counter value from the previous time (n-1st time) to the current time (nth time).

FIG. 5(1) is a table showing the relationship between current I(n) and variable X(n). For example, when the current I(n)=400A, the control unit Cnt refers to the table in FIG. 5(1) and determines the variable X(n)=“15”.

FIG. 5(2) is a table showing the relationship between Y(n-1), current I(n), and variable ΔY(n). For example, when Y(n-1)=5 and current I(n)=400A, the control unit Cnt refers to the table in FIG. 5(2) and determines ΔY(n)=“10”. .

The control unit Cnt determines the current variable Y(n) using Equation 3 below.

Y(n)=Y(n-1)+ΔY(n)...Formula 3

The variable Y(n) is a value that simulates a response delay due to a temperature rise in a portion having a large heat capacity, such as from an element to a temperature sensor. Therefore, the variable Y(n) corresponds to the response delay of the temperature sensor Ts1 and the temperature sensor Ts2 with respect to the temperature rise of the element. The control unit Cnt refers to Equation 3, inputs Y(n-1)=“5” and ΔY(n)=“10”, and calculates the variable Y(n)=“15”.

By substituting equation 3 into equation 2, equation 2 can be rewritten and the counter value Z(n) can be calculated using equation 2' below.

Counter value Z(n)=X(n)+Y(n)...Formula 2'

The control unit Cnt calculates the counter value Z(n) by inputting the calculated variable X(n) = "15" and the calculated variable Y(n) = "15" into the above equation 2'. The control unit Cnt calculates the counter value Z(n)=15+15=“30”.

Next, the control unit Cnt determines the counter upper limit value Z_limit(n) (limiting current) using the following equation 4.

Counter upper limit value Z_limit (n) = Element rated temperature ET - Sensor temperature T - α...Formula 4

The element rated temperature ET is the rated temperature of the switching elements Q1 to Q6. For example, 175°C is set. The sensor temperature T is the current substrate temperature measured by the temperature sensor Ts. The coefficient corresponding to the margin (margin coefficient) α is a value corresponding to the margin of temperature rise. The coefficient corresponding to the margin (margin coefficient) α is a value that can be set when used to calculate the limit current. The coefficient α corresponding to the margin includes an expected amount of temperature rise of the temperature sensor Ts until the next time. For example, "10° C." is set as the coefficient α corresponding to the margin.

The control unit Cnt can easily adjust the parameter of the coefficient α corresponding to the margin. As a result, it is possible to reduce design man-hours.

The control unit Cnt selects the current upper limit value I_limit(n+1) that satisfies the following formula 5 such that the next (n+1th) counter value is equal to or less than the threshold value. Based on the selected current upper limit value I_limit(n+1), the upper limit value of the current that can be output can be set.

X(n+1)+Y(n)+ΔY(n+1)<Z_limit(n)...Formula 5

The current upper limit value I_limit (n+1) is calculated from the table shown in FIG.

FIG. 6 is an example of a table showing the relationship between variables and current. The effective value of current I=X' (n+1st time) is shown. The variable Y(n) indicates the current (nth) counter value. The variable ΔY'(n+1) indicates the next (n+1st) increase in the counter value.

FIG. 6(1) is a table showing the relationship between the current I and the variable X'(n+1). FIG. 6(2) is a table showing the relationship between the current I(n), the variable ΔY(n), and the variable ΔY'(n+1). The control unit Cnt selects the current upper limit value I_limit(n+1) that satisfies the following formula 6 with reference to FIGS. 6(1) and 6(2).

Z'(n+1)=X'(n+1)+Y(n)+ΔY'(n+1)...Formula 6

Applying the above formula 6, when current I = 500A, Z'(n+1) = 20 + 15 + 7 = "42", when current I = 400A, Z'(n + 1) = 15 + 15 + 5 = "35", current I = When the current is 300A, Z'(n+1)=10+15+2='27' is calculated, and when the current I=200A, Z'(n+1)=5+15+0='20' is calculated.

Therefore, for example, when Z(n) = "30" and Z_limit(n) = "38", the control unit Cnt controls the current I = "400A" which is less than or equal to Z_limit(n) = "38". The upper limit value I_limit (n+1) is selected.

FIG. 7 is an example of a graph showing the relationship between counter value Z(n) and current value. When the counter upper limit value Z_limit(n) is set to be equal to or less than Z_limit, when the current I is set, as shown in FIG. When the temperature rises, the current limit based on the current upper limit value I_limit (n+1) decreases.

When the current limit decreases, the control unit Cnt can control the current to be equal to or less than the upper limit value I_limit (n+1) by controlling the duty ratios of the switching elements Q1 to Q6.

According to the above-described embodiment, the control unit Cnt converts the current I(n) into a variable X(n) corresponding to the temperature of the switching elements Q1 to Q6 themselves, and temperature sensors Ts1 and Ts2 corresponding to the temperature rise of the switching elements Q1 to Q6. It can be calculated based on the variable Y(n) corresponding to the response delay. Therefore, the current I(n) can be calculated based on the minimum temperature sensors Ts1 and Ts2, taking into account the response delay of the temperature sensors Ts1 and Ts2. Thereby, it is possible to improve the accuracy of temperature measurement while suppressing an increase in product cost. As a result, the temperatures of the switching elements Q1 to Q6 that constitute the inverter 1 can be calculated with high accuracy, and the switching elements Q1 to Q6 can be protected from overheating.

Furthermore, the control unit Cnt can easily adjust parameters such as the coefficient α corresponding to the margin. As a result, it is possible to reduce the number of design steps when the semiconductor device is used for multiple purposes.

<Modification 1>
The temperature sensor Ts may measure the temperature of the components that make up the inverter 1 (hereinafter also referred to as "component temperature"). For example, the temperature sensor Ts may measure the temperature of components constituting the vehicle, such as the inverter 1 and the control unit Cnt.

1 Inverter M Motors Si1, Si2 Current detection section C Capacitors Ts, Ts1, Ts2 Temperature sensor B Power storage device Cnt Control section Q1 to Q6 Switching elements D1 to D6 Diode Hs Heat sink P Plate body

Claims (3)

Elements that constitute a semiconductor device,
temperature measuring means for measuring the temperature generated by the element;
a current detection unit that detects a current flowing through the element;
a control unit that controls the element;
The control unit includes:
A counter value obtained at a predetermined time is calculated from a parameter that affects heat generation of the element, and is added to a counter value obtained from the result of the temperature measuring means, so that the estimated element temperature does not exceed a predetermined temperature. It calculates the limiting current,
As the parameter,
an element temperature variable corresponding to the temperature of the element itself;
a simulating temperature variable that simulates a temperature rise of a portion that is heat-conductingly connected to the element and has a large heat capacity in response to a temperature rise of the element;
The semiconductor device characterized in that the control section has a counter increment extraction means for calculating a limiting current based on the element temperature variable and the simulated temperature variable from the current value detected by the current detection section. . The arrangement direction of the elements and the extending direction of a heat sink plate that cools the elements are the same direction,
2. The semiconductor device according to claim 1, wherein the temperature measuring means is arranged upstream and downstream of the heat sink. The control unit includes:
It has a counter upper limit value used to calculate the limit current,
3. The semiconductor device according to claim 1, wherein a margin coefficient corresponding to a temperature rise margin used for calculating the limited current can be set.